diff --git a/app/schemas/org.libremail.data.local.LibreMailDatabase/10.json b/app/schemas/org.libremail.data.local.LibreMailDatabase/10.json
new file mode 100644
index 0000000..65389fd
--- /dev/null
+++ b/app/schemas/org.libremail.data.local.LibreMailDatabase/10.json
@@ -0,0 +1,585 @@
+{
+  "formatVersion": 1,
+  "database": {
+    "version": 10,
+    "identityHash": "dda823c68d6b6207f3b648b46a0182e6",
+    "entities": [
+      {
+        "tableName": "accounts",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `email` TEXT NOT NULL, `displayName` TEXT NOT NULL, `authType` TEXT NOT NULL, `imap_host` TEXT NOT NULL, `imap_port` INTEGER NOT NULL, `imap_security` TEXT NOT NULL, `smtp_host` TEXT NOT NULL, `smtp_port` INTEGER NOT NULL, `smtp_security` TEXT NOT NULL, PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "email",
+            "columnName": "email",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "displayName",
+            "columnName": "displayName",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "authType",
+            "columnName": "authType",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "imap.host",
+            "columnName": "imap_host",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "imap.port",
+            "columnName": "imap_port",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "imap.security",
+            "columnName": "imap_security",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "smtp.host",
+            "columnName": "smtp_host",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "smtp.port",
+            "columnName": "smtp_port",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "smtp.security",
+            "columnName": "smtp_security",
+            "affinity": "TEXT",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        }
+      },
+      {
+        "tableName": "account_settings",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`accountId` TEXT NOT NULL, `signature` TEXT NOT NULL, `signatureEnabled` INTEGER NOT NULL, `notificationsEnabled` INTEGER NOT NULL, PRIMARY KEY(`accountId`), FOREIGN KEY(`accountId`) REFERENCES `accounts`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE )",
+        "fields": [
+          {
+            "fieldPath": "accountId",
+            "columnName": "accountId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "signature",
+            "columnName": "signature",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "signatureEnabled",
+            "columnName": "signatureEnabled",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "notificationsEnabled",
+            "columnName": "notificationsEnabled",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "accountId"
+          ]
+        },
+        "foreignKeys": [
+          {
+            "table": "accounts",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "accountId"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "messages",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `accountId` TEXT NOT NULL, `sender` TEXT NOT NULL, `senderEmail` TEXT NOT NULL, `subject` TEXT NOT NULL, `snippet` TEXT NOT NULL, `body` TEXT NOT NULL, `isHtml` INTEGER NOT NULL, `timestampMillis` INTEGER NOT NULL, `isRead` INTEGER NOT NULL, `isStarred` INTEGER NOT NULL, `folder` TEXT NOT NULL DEFAULT 'INBOX', `inInbox` INTEGER NOT NULL, `bodyFetched` INTEGER NOT NULL, PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "accountId",
+            "columnName": "accountId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "sender",
+            "columnName": "sender",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "senderEmail",
+            "columnName": "senderEmail",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "subject",
+            "columnName": "subject",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "snippet",
+            "columnName": "snippet",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "body",
+            "columnName": "body",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "isHtml",
+            "columnName": "isHtml",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "timestampMillis",
+            "columnName": "timestampMillis",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "isRead",
+            "columnName": "isRead",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "isStarred",
+            "columnName": "isStarred",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "folder",
+            "columnName": "folder",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "'INBOX'"
+          },
+          {
+            "fieldPath": "inInbox",
+            "columnName": "inInbox",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "bodyFetched",
+            "columnName": "bodyFetched",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_messages_accountId",
+            "unique": false,
+            "columnNames": [
+              "accountId"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_messages_accountId` ON `${TABLE_NAME}` (`accountId`)"
+          },
+          {
+            "name": "index_messages_timestampMillis",
+            "unique": false,
+            "columnNames": [
+              "timestampMillis"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_messages_timestampMillis` ON `${TABLE_NAME}` (`timestampMillis`)"
+          }
+        ]
+      },
+      {
+        "tableName": "credentials",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`accountId` TEXT NOT NULL, `encryptedSecret` TEXT NOT NULL, PRIMARY KEY(`accountId`))",
+        "fields": [
+          {
+            "fieldPath": "accountId",
+            "columnName": "accountId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "encryptedSecret",
+            "columnName": "encryptedSecret",
+            "affinity": "TEXT",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "accountId"
+          ]
+        }
+      },
+      {
+        "tableName": "attachments",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`messageId` TEXT NOT NULL, `partIndex` INTEGER NOT NULL, `filename` TEXT NOT NULL, `mimeType` TEXT NOT NULL, `sizeBytes` INTEGER NOT NULL, PRIMARY KEY(`messageId`, `partIndex`), FOREIGN KEY(`messageId`) REFERENCES `messages`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE )",
+        "fields": [
+          {
+            "fieldPath": "messageId",
+            "columnName": "messageId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "partIndex",
+            "columnName": "partIndex",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "filename",
+            "columnName": "filename",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "mimeType",
+            "columnName": "mimeType",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "sizeBytes",
+            "columnName": "sizeBytes",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "messageId",
+            "partIndex"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_attachments_messageId",
+            "unique": false,
+            "columnNames": [
+              "messageId"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_attachments_messageId` ON `${TABLE_NAME}` (`messageId`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "messages",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "messageId"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "outbox",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `accountId` TEXT NOT NULL, `toAddresses` TEXT NOT NULL, `ccAddresses` TEXT NOT NULL, `subject` TEXT NOT NULL, `body` TEXT NOT NULL, `createdAt` INTEGER NOT NULL, `lastError` TEXT, `bodyHtml` TEXT, PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "accountId",
+            "columnName": "accountId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "toAddresses",
+            "columnName": "toAddresses",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "ccAddresses",
+            "columnName": "ccAddresses",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "subject",
+            "columnName": "subject",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "body",
+            "columnName": "body",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "createdAt",
+            "columnName": "createdAt",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "lastError",
+            "columnName": "lastError",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "bodyHtml",
+            "columnName": "bodyHtml",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        }
+      },
+      {
+        "tableName": "drafts",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `accountId` TEXT, `toAddresses` TEXT NOT NULL, `ccAddresses` TEXT NOT NULL, `subject` TEXT NOT NULL, `body` TEXT NOT NULL, `updatedAt` INTEGER NOT NULL, `attachments` TEXT NOT NULL, `bodyHtml` TEXT, PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "accountId",
+            "columnName": "accountId",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "toAddresses",
+            "columnName": "toAddresses",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "ccAddresses",
+            "columnName": "ccAddresses",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "subject",
+            "columnName": "subject",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "body",
+            "columnName": "body",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "updatedAt",
+            "columnName": "updatedAt",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "attachments",
+            "columnName": "attachments",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "bodyHtml",
+            "columnName": "bodyHtml",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        }
+      },
+      {
+        "tableName": "folders",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`accountId` TEXT NOT NULL, `fullName` TEXT NOT NULL, `displayName` TEXT NOT NULL, `role` TEXT NOT NULL, `selectable` INTEGER NOT NULL, `sortOrder` INTEGER NOT NULL, PRIMARY KEY(`accountId`, `fullName`))",
+        "fields": [
+          {
+            "fieldPath": "accountId",
+            "columnName": "accountId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "fullName",
+            "columnName": "fullName",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "displayName",
+            "columnName": "displayName",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "role",
+            "columnName": "role",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "selectable",
+            "columnName": "selectable",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "sortOrder",
+            "columnName": "sortOrder",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "accountId",
+            "fullName"
+          ]
+        }
+      },
+      {
+        "tableName": "signatures",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `accountId` TEXT NOT NULL, `name` TEXT NOT NULL, `contentHtml` TEXT NOT NULL, `isDefault` INTEGER NOT NULL, PRIMARY KEY(`id`), FOREIGN KEY(`accountId`) REFERENCES `accounts`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "accountId",
+            "columnName": "accountId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "name",
+            "columnName": "name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "contentHtml",
+            "columnName": "contentHtml",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "isDefault",
+            "columnName": "isDefault",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_signatures_accountId",
+            "unique": false,
+            "columnNames": [
+              "accountId"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_signatures_accountId` ON `${TABLE_NAME}` (`accountId`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "accounts",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "accountId"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      }
+    ],
+    "setupQueries": [
+      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
+      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, 'dda823c68d6b6207f3b648b46a0182e6')"
+    ]
+  }
+}
\ No newline at end of file
diff --git a/app/src/androidTest/kotlin/org/libremail/ui/compose/ComposeScreenTest.kt b/app/src/androidTest/kotlin/org/libremail/ui/compose/ComposeScreenTest.kt
index f79725a..97777c4 100644
--- a/app/src/androidTest/kotlin/org/libremail/ui/compose/ComposeScreenTest.kt
+++ b/app/src/androidTest/kotlin/org/libremail/ui/compose/ComposeScreenTest.kt
@@ -24,6 +24,7 @@ import org.libremail.R
 import org.libremail.contacts.ContactsRepository
 import org.libremail.data.local.LibreMailDatabase
 import org.libremail.data.settings.AccountSettingsRepository
+import org.libremail.data.settings.SignatureRepository
 import org.libremail.domain.model.Account
 import org.libremail.domain.model.AuthType
 import org.libremail.domain.model.MailSecurity
@@ -81,6 +82,7 @@ class ComposeScreenTest {
             accountRepository = FakeAccountRepository(accounts = listOf(account)),
             contactsRepository = ContactsRepository(context),
             accountSettingsRepository = AccountSettingsRepository(database.accountSettingsDao()),
+            signatureRepository = SignatureRepository(database.signatureDao()),
         )
         composeTestRule.setContent {
             LibreMailTheme(darkTheme = false, dynamicColor = false) {
diff --git a/app/src/androidTest/kotlin/org/libremail/ui/settings/AccountSettingsScreenTest.kt b/app/src/androidTest/kotlin/org/libremail/ui/settings/AccountSettingsScreenTest.kt
index d4f26b7..8bafcf7 100644
--- a/app/src/androidTest/kotlin/org/libremail/ui/settings/AccountSettingsScreenTest.kt
+++ b/app/src/androidTest/kotlin/org/libremail/ui/settings/AccountSettingsScreenTest.kt
@@ -6,7 +6,6 @@ import androidx.activity.ComponentActivity
 import androidx.compose.ui.test.junit4.createAndroidComposeRule
 import androidx.compose.ui.test.onNodeWithText
 import androidx.compose.ui.test.performClick
-import androidx.compose.ui.test.performTextInput
 import androidx.lifecycle.SavedStateHandle
 import androidx.room.Room
 import androidx.test.core.app.ApplicationProvider
@@ -19,6 +18,7 @@ import org.libremail.R
 import org.libremail.data.local.LibreMailDatabase
 import org.libremail.data.local.toEntity
 import org.libremail.data.settings.AccountSettingsRepository
+import org.libremail.data.settings.SignatureRepository
 import org.libremail.domain.model.Account
 import org.libremail.domain.model.AuthType
 import org.libremail.domain.model.MailSecurity
@@ -48,6 +48,8 @@ class AccountSettingsScreenTest {
 
     private fun string(resId: Int) = composeTestRule.activity.getString(resId)
 
+    private var manageSignaturesClicked = false
+
     private fun setContent(): AccountSettingsRepository {
         val context = ApplicationProvider.getApplicationContext<Context>()
         // Intentionally not closed in an @After: the ViewModel's `settings` Room Flow (kept alive by
@@ -64,24 +66,27 @@ class AccountSettingsScreenTest {
             savedStateHandle = SavedStateHandle(mapOf(Routes.ACCOUNT_SETTINGS_ARG_ID to account.id)),
             accountRepository = FakeAccountRepository(accounts = listOf(account)),
             accountSettingsRepository = repository,
+            signatureRepository = SignatureRepository(db.signatureDao()),
         )
         composeTestRule.setContent {
             LibreMailTheme(darkTheme = false, dynamicColor = false) {
-                AccountSettingsScreen(onBack = {}, viewModel = viewModel)
+                AccountSettingsScreen(
+                    onBack = {},
+                    onManageSignatures = { manageSignaturesClicked = true },
+                    viewModel = viewModel,
+                )
             }
         }
         return repository
     }
 
     @Test
-    fun editingSignature_persistsThroughTheRepository() {
-        val repository = setContent()
+    fun manageSignatures_opensTheSignaturesScreen() {
+        setContent()
 
-        composeTestRule.onNodeWithText(string(R.string.settings_signature_hint)).performTextInput("Cheers")
+        composeTestRule.onNodeWithText(string(R.string.settings_signatures_manage)).performClick()
 
-        composeTestRule.waitUntil(5_000) {
-            runBlocking { repository.get(account.id).signature } == "Cheers"
-        }
+        composeTestRule.waitUntil(5_000) { manageSignaturesClicked }
     }
 
     @Test
diff --git a/app/src/main/kotlin/org/libremail/data/ReplyBuilder.kt b/app/src/main/kotlin/org/libremail/data/ReplyBuilder.kt
index ec0164e..a8067c7 100644
--- a/app/src/main/kotlin/org/libremail/data/ReplyBuilder.kt
+++ b/app/src/main/kotlin/org/libremail/data/ReplyBuilder.kt
@@ -2,40 +2,55 @@
 package org.libremail.data
 
 import org.libremail.domain.model.ReplyMode
+import org.libremail.mail.HtmlToText
 import org.libremail.mail.ReplyContext
+import org.libremail.richtext.RichTextContent
+import org.libremail.richtext.RichTextHtml
 import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
 
-/** The pre-filled compose fields for a reply/forward (everything else the user fills in). */
-data class ReplyContent(val to: String, val cc: String, val subject: String, val body: String)
+/**
+ * The pre-filled compose fields for a reply/forward. [body] is the plaintext form; [bodyHtml] is the
+ * matching HTML (the quote rendered as a `<blockquote>`), so the reply can go out as
+ * `multipart/alternative` without the user having to re-format the quote.
+ */
+data class ReplyContent(val to: String, val cc: String, val subject: String, val body: String, val bodyHtml: String)
 
 /**
  * Pure builder that turns an original message ([ReplyContext]) into the pre-filled compose fields for a
  * reply, reply-all, or forward. Kept free of Android/IMAP dependencies so it can be unit-tested directly.
+ *
+ * HTML originals are quoted by first reducing them to readable text (via [HtmlToText]) and then
+ * quoting that — never by prefixing "> " onto raw tags — so the quote can never corrupt the markup.
+ * The plaintext quote's "> " / attribution structure is then rendered to a clean `<blockquote>` for
+ * the HTML alternative.
  */
 object ReplyBuilder {
 
     fun build(context: ReplyContext, mode: ReplyMode, selfEmail: String): ReplyContent = when (mode) {
-        ReplyMode.REPLY -> ReplyContent(
-            to = context.fromEmail,
-            cc = "",
-            subject = prefixedSubject(context.subject, "Re:"),
-            body = quotedReply(context),
-        )
+        ReplyMode.REPLY -> reply(context, cc = "")
+        ReplyMode.REPLY_ALL -> reply(context, cc = replyAllCc(context, selfEmail).joinToString(", "))
+        ReplyMode.FORWARD -> {
+            val body = forwardedBody(context)
+            ReplyContent(
+                to = "",
+                cc = "",
+                subject = prefixedSubject(context.subject, "Fwd:"),
+                body = body,
+                bodyHtml = htmlOf(body),
+            )
+        }
+    }
 
-        ReplyMode.REPLY_ALL -> ReplyContent(
+    private fun reply(context: ReplyContext, cc: String): ReplyContent {
+        val body = quotedReply(context)
+        return ReplyContent(
             to = context.fromEmail,
-            cc = replyAllCc(context, selfEmail).joinToString(", "),
+            cc = cc,
             subject = prefixedSubject(context.subject, "Re:"),
-            body = quotedReply(context),
-        )
-
-        ReplyMode.FORWARD -> ReplyContent(
-            to = "",
-            cc = "",
-            subject = prefixedSubject(context.subject, "Fwd:"),
-            body = forwardedBody(context),
+            body = body,
+            bodyHtml = htmlOf(body),
         )
     }
 
@@ -68,15 +83,12 @@ object ReplyBuilder {
         append(bodyText(context))
     }
 
-    /** The original body as plain text (HTML stripped), suitable for quoting in a plain-text compose. */
-    private fun bodyText(context: ReplyContext): String = if (context.isHtml) htmlToText(context.body) else context.body
+    /** The original body as plain text (HTML stripped), suitable for quoting in a compose field. */
+    private fun bodyText(context: ReplyContext): String =
+        if (context.isHtml) HtmlToText.convert(context.body) else context.body
 
-    private fun htmlToText(html: String): String = html
-        .replace(Regex("(?i)<br\\s*/?>"), "\n")
-        .replace(Regex("(?i)</p\\s*>"), "\n\n")
-        .replace(Regex("<[^>]*>"), "")
-        .replace(Regex("[ \\t]+"), " ")
-        .trim()
+    /** Renders the plaintext quote (with its "> " markers) to the equivalent clean HTML. */
+    private fun htmlOf(body: String): String = RichTextHtml.toHtml(RichTextContent(body))
 
     private fun formatDate(millis: Long): String =
         SimpleDateFormat("MMM d, yyyy, h:mm a", Locale.US).format(Date(millis))
diff --git a/app/src/main/kotlin/org/libremail/data/SignatureBlock.kt b/app/src/main/kotlin/org/libremail/data/SignatureBlock.kt
new file mode 100644
index 0000000..a46b109
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/data/SignatureBlock.kt
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.data
+
+import org.libremail.domain.model.Signature
+import org.libremail.richtext.RichTextContent
+import org.libremail.richtext.RichTextHtml
+
+/**
+ * A signature rendered into both forms the composer needs: [plain] for the plaintext body/fallback
+ * and [html] for the HTML body. The two are kept in sync — parsing [html] back through the rich-text
+ * model yields exactly [plain] — so the editor shows the same content whichever it seeds from, and a
+ * From-account swap can strip the previously applied block from either representation.
+ *
+ * The block opens with the RFC 3676 "-- " delimiter so receiving clients recognize it as a signature.
+ */
+data class SignatureBlock(val plain: String, val html: String) {
+    val isEmpty: Boolean get() = plain.isEmpty() && html.isEmpty()
+
+    companion object {
+        val EMPTY = SignatureBlock("", "")
+
+        /** The block for [signature], or [EMPTY] when there is none / it is blank. */
+        fun of(signature: Signature?): SignatureBlock {
+            if (signature == null) return EMPTY
+            val plainSig = signature.plainText().trimEnd()
+            if (plainSig.isBlank() && signature.html.isBlank()) return EMPTY
+            return SignatureBlock(
+                plain = "$DELIMITER_PLAIN$plainSig",
+                html = RichTextHtml.toHtml(RichTextContent(DELIMITER_PLAIN)) + signature.html,
+            )
+        }
+
+        private const val DELIMITER_PLAIN = "\n\n-- \n"
+    }
+}
diff --git a/app/src/main/kotlin/org/libremail/data/local/LibreMailDatabase.kt b/app/src/main/kotlin/org/libremail/data/local/LibreMailDatabase.kt
index 0b1b2e5..2825a61 100644
--- a/app/src/main/kotlin/org/libremail/data/local/LibreMailDatabase.kt
+++ b/app/src/main/kotlin/org/libremail/data/local/LibreMailDatabase.kt
@@ -11,6 +11,7 @@ import org.libremail.data.local.dao.DraftDao
 import org.libremail.data.local.dao.FolderDao
 import org.libremail.data.local.dao.MessageDao
 import org.libremail.data.local.dao.OutboxDao
+import org.libremail.data.local.dao.SignatureDao
 import org.libremail.data.local.entity.AccountEntity
 import org.libremail.data.local.entity.AccountSettingsEntity
 import org.libremail.data.local.entity.AttachmentEntity
@@ -19,6 +20,7 @@ import org.libremail.data.local.entity.DraftEntity
 import org.libremail.data.local.entity.FolderEntity
 import org.libremail.data.local.entity.MessageEntity
 import org.libremail.data.local.entity.OutboxEntity
+import org.libremail.data.local.entity.SignatureEntity
 
 @Database(
     entities = [
@@ -30,8 +32,9 @@ import org.libremail.data.local.entity.OutboxEntity
         OutboxEntity::class,
         DraftEntity::class,
         FolderEntity::class,
+        SignatureEntity::class,
     ],
-    version = 9,
+    version = 10,
     exportSchema = true,
 )
 abstract class LibreMailDatabase : RoomDatabase() {
@@ -43,4 +46,5 @@ abstract class LibreMailDatabase : RoomDatabase() {
     abstract fun outboxDao(): OutboxDao
     abstract fun draftDao(): DraftDao
     abstract fun folderDao(): FolderDao
+    abstract fun signatureDao(): SignatureDao
 }
diff --git a/app/src/main/kotlin/org/libremail/data/local/Mappers.kt b/app/src/main/kotlin/org/libremail/data/local/Mappers.kt
index bf975f1..9c4773d 100644
--- a/app/src/main/kotlin/org/libremail/data/local/Mappers.kt
+++ b/app/src/main/kotlin/org/libremail/data/local/Mappers.kt
@@ -162,6 +162,7 @@ internal fun DraftEntity.toDomain(): Draft = Draft(
     subject = subject,
     body = body,
     updatedAt = updatedAt,
+    bodyHtml = bodyHtml,
     attachments = attachments.toOutgoingAttachments(),
 )
 
@@ -174,6 +175,7 @@ internal fun Draft.toEntity(): DraftEntity = DraftEntity(
     body = body,
     updatedAt = updatedAt,
     attachments = attachments.toJson(),
+    bodyHtml = bodyHtml,
 )
 
 /** Serializes draft attachments as a JSON array of {uri, name} objects ("" when empty). */
@@ -202,6 +204,7 @@ internal fun OutboxEntity.toDomain(): OutboxMessage = OutboxMessage(
     body = body,
     createdAt = createdAt,
     lastError = lastError,
+    bodyHtml = bodyHtml,
 )
 
 private fun String.toMailSecurity(): MailSecurity = runCatching {
diff --git a/app/src/main/kotlin/org/libremail/data/local/Migrations.kt b/app/src/main/kotlin/org/libremail/data/local/Migrations.kt
index 0338ce3..7093a3a 100644
--- a/app/src/main/kotlin/org/libremail/data/local/Migrations.kt
+++ b/app/src/main/kotlin/org/libremail/data/local/Migrations.kt
@@ -171,3 +171,35 @@ val MIGRATION_8_9 = object : Migration(8, 9) {
         )
     }
 }
+
+/**
+ * v9 -> v10: rich composition (preserves existing data).
+ *  - `drafts`/`outbox`: add a nullable `bodyHtml` column carrying the HTML form of the body when a
+ *    message was composed with formatting (null = plaintext-only, sent/kept exactly as before).
+ *  - add the `signatures` table (multiple named signatures per account, one default), with a
+ *    cascading foreign key to `accounts`, and backfill each account's existing per-account settings
+ *    signature as its default signature so nobody loses one on upgrade.
+ */
+val MIGRATION_9_10 = object : Migration(9, 10) {
+    override fun migrate(db: SupportSQLiteDatabase) {
+        db.execSQL("ALTER TABLE `drafts` ADD COLUMN `bodyHtml` TEXT")
+        db.execSQL("ALTER TABLE `outbox` ADD COLUMN `bodyHtml` TEXT")
+        db.execSQL(
+            "CREATE TABLE IF NOT EXISTS `signatures` (" +
+                "`id` TEXT NOT NULL, `accountId` TEXT NOT NULL, `name` TEXT NOT NULL, " +
+                "`contentHtml` TEXT NOT NULL, `isDefault` INTEGER NOT NULL, PRIMARY KEY(`id`), " +
+                "FOREIGN KEY(`accountId`) REFERENCES `accounts`(`id`) " +
+                "ON UPDATE NO ACTION ON DELETE CASCADE)",
+        )
+        db.execSQL("CREATE INDEX IF NOT EXISTS `index_signatures_accountId` ON `signatures` (`accountId`)")
+        // Preserve any existing plain-text per-account signature as that account's default signature.
+        // Newlines become <br> so the HTML keeps the original line breaks; other characters are rare
+        // in signatures and pass through unescaped.
+        db.execSQL(
+            "INSERT INTO `signatures` (`id`, `accountId`, `name`, `contentHtml`, `isDefault`) " +
+                "SELECT `accountId` || ':default-signature', `accountId`, 'Signature', " +
+                "replace(`signature`, char(10), '<br>'), 1 " +
+                "FROM `account_settings` WHERE `signature` <> ''",
+        )
+    }
+}
diff --git a/app/src/main/kotlin/org/libremail/data/local/dao/SignatureDao.kt b/app/src/main/kotlin/org/libremail/data/local/dao/SignatureDao.kt
new file mode 100644
index 0000000..ddf12c9
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/data/local/dao/SignatureDao.kt
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.data.local.dao
+
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import androidx.room.Transaction
+import kotlinx.coroutines.flow.Flow
+import org.libremail.data.local.entity.SignatureEntity
+
+@Dao
+interface SignatureDao {
+    @Query("SELECT * FROM signatures WHERE accountId = :accountId ORDER BY isDefault DESC, name COLLATE NOCASE")
+    fun observeForAccount(accountId: String): Flow<List<SignatureEntity>>
+
+    @Query("SELECT * FROM signatures WHERE id = :id LIMIT 1")
+    suspend fun getById(id: String): SignatureEntity?
+
+    @Query("SELECT * FROM signatures WHERE accountId = :accountId AND isDefault = 1 LIMIT 1")
+    suspend fun getDefault(accountId: String): SignatureEntity?
+
+    @Query("SELECT * FROM signatures WHERE accountId = :accountId ORDER BY name COLLATE NOCASE LIMIT 1")
+    suspend fun firstForAccount(accountId: String): SignatureEntity?
+
+    @Query("SELECT COUNT(*) FROM signatures WHERE accountId = :accountId")
+    suspend fun countForAccount(accountId: String): Int
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun upsert(signature: SignatureEntity)
+
+    @Query("DELETE FROM signatures WHERE id = :id")
+    suspend fun delete(id: String)
+
+    @Query("UPDATE signatures SET isDefault = 0 WHERE accountId = :accountId")
+    suspend fun clearDefault(accountId: String)
+
+    @Query("UPDATE signatures SET isDefault = 1 WHERE id = :id")
+    suspend fun markDefault(id: String)
+
+    /** Makes [id] the account's sole default in one transaction (clears the others first). */
+    @Transaction
+    suspend fun setDefault(accountId: String, id: String) {
+        clearDefault(accountId)
+        markDefault(id)
+    }
+}
diff --git a/app/src/main/kotlin/org/libremail/data/local/entity/DraftEntity.kt b/app/src/main/kotlin/org/libremail/data/local/entity/DraftEntity.kt
index ed6dd3b..b781e8c 100644
--- a/app/src/main/kotlin/org/libremail/data/local/entity/DraftEntity.kt
+++ b/app/src/main/kotlin/org/libremail/data/local/entity/DraftEntity.kt
@@ -16,4 +16,6 @@ data class DraftEntity(
     val updatedAt: Long,
     /** JSON array of the draft's attachments ([uri, name] pairs); empty string when there are none. */
     val attachments: String = "",
+    /** HTML form of [body] when the draft carries formatting; null for plaintext drafts. */
+    val bodyHtml: String? = null,
 )
diff --git a/app/src/main/kotlin/org/libremail/data/local/entity/OutboxEntity.kt b/app/src/main/kotlin/org/libremail/data/local/entity/OutboxEntity.kt
index 96d5f44..6ade954 100644
--- a/app/src/main/kotlin/org/libremail/data/local/entity/OutboxEntity.kt
+++ b/app/src/main/kotlin/org/libremail/data/local/entity/OutboxEntity.kt
@@ -15,4 +15,6 @@ data class OutboxEntity(
     val body: String,
     val createdAt: Long,
     val lastError: String? = null,
+    /** HTML form of [body] when composed with formatting; null sends `text/plain` only. */
+    val bodyHtml: String? = null,
 )
diff --git a/app/src/main/kotlin/org/libremail/data/local/entity/SignatureEntity.kt b/app/src/main/kotlin/org/libremail/data/local/entity/SignatureEntity.kt
new file mode 100644
index 0000000..23c1c13
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/data/local/entity/SignatureEntity.kt
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.data.local.entity
+
+import androidx.room.Entity
+import androidx.room.ForeignKey
+import androidx.room.Index
+import androidx.room.PrimaryKey
+
+/**
+ * One saved signature. The [accountId] foreign key cascades on delete, so removing an account drops
+ * its signatures. [isDefault] marks the one auto-inserted when composing from the account; the
+ * repository keeps at most one default per account.
+ */
+@Entity(
+    tableName = "signatures",
+    foreignKeys = [
+        ForeignKey(
+            entity = AccountEntity::class,
+            parentColumns = ["id"],
+            childColumns = ["accountId"],
+            onDelete = ForeignKey.CASCADE,
+        ),
+    ],
+    indices = [Index("accountId")],
+)
+data class SignatureEntity(
+    @PrimaryKey val id: String,
+    val accountId: String,
+    val name: String,
+    val contentHtml: String,
+    val isDefault: Boolean = false,
+)
diff --git a/app/src/main/kotlin/org/libremail/data/repository/MailRepositoryImpl.kt b/app/src/main/kotlin/org/libremail/data/repository/MailRepositoryImpl.kt
index 94657d8..6f941da 100644
--- a/app/src/main/kotlin/org/libremail/data/repository/MailRepositoryImpl.kt
+++ b/app/src/main/kotlin/org/libremail/data/repository/MailRepositoryImpl.kt
@@ -8,6 +8,7 @@ import jakarta.mail.Flags
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
 import org.libremail.data.ReplyBuilder
+import org.libremail.data.SignatureBlock
 import org.libremail.data.local.dao.AccountDao
 import org.libremail.data.local.dao.AttachmentDao
 import org.libremail.data.local.dao.DraftDao
@@ -20,6 +21,7 @@ import org.libremail.data.local.entity.OutboxEntity
 import org.libremail.data.local.toDomain
 import org.libremail.data.local.toEntity
 import org.libremail.data.settings.AccountSettingsRepository
+import org.libremail.data.settings.SignatureRepository
 import org.libremail.data.sync.MailConnectionFactory
 import org.libremail.data.sync.SendScheduler
 import org.libremail.domain.model.Attachment
@@ -52,6 +54,7 @@ class MailRepositoryImpl @Inject constructor(
     private val connectionFactory: MailConnectionFactory,
     private val sendScheduler: SendScheduler,
     private val accountSettingsRepository: AccountSettingsRepository,
+    private val signatureRepository: SignatureRepository,
 ) : MailRepository {
 
     override fun observeMessages(): Flow<List<Message>> = messageDao.observeAll().map { rows ->
@@ -191,9 +194,15 @@ class MailRepositoryImpl @Inject constructor(
         val params = connectionFactory.imapParamsFor(account)
         val context = imapClient.fetchForReply(params, entity.folder, uidOf(messageId))
         val content = ReplyBuilder.build(context, mode, account.email)
-        // Bake the sending account's signature into the reply/forward body so it round-trips as part
-        // of the draft (compose won't re-append for drafts).
-        val signature = accountSettingsRepository.get(entity.accountId).signatureBlock()
+        // Bake the sending account's default signature into the reply/forward body — above the quoted
+        // original — so it round-trips as part of the draft (compose won't re-append for drafts). Both
+        // the plaintext and HTML forms are stored so the reply can go out as multipart/alternative.
+        val settings = accountSettingsRepository.get(entity.accountId)
+        val sig = if (settings.signatureEnabled) {
+            SignatureBlock.of(signatureRepository.getDefault(entity.accountId))
+        } else {
+            SignatureBlock.EMPTY
+        }
         val draftId = UUID.randomUUID().toString()
         saveDraft(
             Draft(
@@ -202,8 +211,9 @@ class MailRepositoryImpl @Inject constructor(
                 to = content.to,
                 cc = content.cc,
                 subject = content.subject,
-                body = content.body + signature,
+                body = sig.plain + content.body,
                 updatedAt = System.currentTimeMillis(),
+                bodyHtml = sig.html + content.bodyHtml,
                 attachments = emptyList(),
             ),
         )
@@ -269,6 +279,7 @@ class MailRepositoryImpl @Inject constructor(
                 subject = outgoing.subject,
                 body = outgoing.body,
                 createdAt = System.currentTimeMillis(),
+                bodyHtml = outgoing.bodyHtml,
             ),
         )
         sendScheduler.sendNow()
diff --git a/app/src/main/kotlin/org/libremail/data/settings/SignatureRepository.kt b/app/src/main/kotlin/org/libremail/data/settings/SignatureRepository.kt
new file mode 100644
index 0000000..5bc3955
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/data/settings/SignatureRepository.kt
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.data.settings
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import org.libremail.data.local.dao.SignatureDao
+import org.libremail.data.local.entity.SignatureEntity
+import org.libremail.domain.model.Signature
+import java.util.UUID
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * CRUD for per-account signatures, keeping the "at most one default per account" invariant. The
+ * first signature created for an account becomes its default automatically; deleting the default
+ * promotes another (if any) so an account with signatures always has one to auto-insert.
+ */
+@Singleton
+class SignatureRepository @Inject constructor(private val dao: SignatureDao) {
+
+    fun observeForAccount(accountId: String): Flow<List<Signature>> =
+        dao.observeForAccount(accountId).map { rows -> rows.map { it.toDomain() } }
+
+    suspend fun get(id: String): Signature? = dao.getById(id)?.toDomain()
+
+    suspend fun getDefault(accountId: String): Signature? = dao.getDefault(accountId)?.toDomain()
+
+    /** Creates a signature; makes it the default when it is the account's first. Returns its id. */
+    suspend fun create(accountId: String, name: String, html: String): String {
+        val id = UUID.randomUUID().toString()
+        val isFirst = dao.countForAccount(accountId) == 0
+        dao.upsert(SignatureEntity(id, accountId, name, html, isDefault = isFirst))
+        return id
+    }
+
+    suspend fun update(id: String, name: String, html: String) {
+        val existing = dao.getById(id) ?: return
+        dao.upsert(existing.copy(name = name, contentHtml = html))
+    }
+
+    suspend fun delete(id: String) {
+        val existing = dao.getById(id) ?: return
+        dao.delete(id)
+        // If we removed the default, promote the account's first remaining signature.
+        if (existing.isDefault) {
+            dao.firstForAccount(existing.accountId)?.let { dao.markDefault(it.id) }
+        }
+    }
+
+    suspend fun setDefault(accountId: String, id: String) = dao.setDefault(accountId, id)
+
+    private fun SignatureEntity.toDomain() = Signature(id, accountId, name, contentHtml, isDefault)
+}
diff --git a/app/src/main/kotlin/org/libremail/data/sync/SendWorker.kt b/app/src/main/kotlin/org/libremail/data/sync/SendWorker.kt
index 840182c..1af8bee 100644
--- a/app/src/main/kotlin/org/libremail/data/sync/SendWorker.kt
+++ b/app/src/main/kotlin/org/libremail/data/sync/SendWorker.kt
@@ -56,6 +56,7 @@ class SendWorker @AssistedInject constructor(
                     cc = entity.ccAddresses,
                     subject = entity.subject,
                     body = entity.body,
+                    bodyHtml = entity.bodyHtml,
                 )
                 val files = orderedAttachments(attachmentDir)
                 if (account.authType == AuthType.OAUTH_OUTLOOK) {
diff --git a/app/src/main/kotlin/org/libremail/di/DatabaseModule.kt b/app/src/main/kotlin/org/libremail/di/DatabaseModule.kt
index 8e93ea3..68e8a01 100644
--- a/app/src/main/kotlin/org/libremail/di/DatabaseModule.kt
+++ b/app/src/main/kotlin/org/libremail/di/DatabaseModule.kt
@@ -21,6 +21,7 @@ import org.libremail.data.local.MIGRATION_5_6
 import org.libremail.data.local.MIGRATION_6_7
 import org.libremail.data.local.MIGRATION_7_8
 import org.libremail.data.local.MIGRATION_8_9
+import org.libremail.data.local.MIGRATION_9_10
 import org.libremail.data.local.dao.AccountDao
 import org.libremail.data.local.dao.AccountSettingsDao
 import org.libremail.data.local.dao.AttachmentDao
@@ -29,6 +30,7 @@ import org.libremail.data.local.dao.DraftDao
 import org.libremail.data.local.dao.FolderDao
 import org.libremail.data.local.dao.MessageDao
 import org.libremail.data.local.dao.OutboxDao
+import org.libremail.data.local.dao.SignatureDao
 import org.libremail.data.security.DatabaseKeyStore
 import org.libremail.data.settings.SettingsRepository
 import javax.inject.Singleton
@@ -54,6 +56,7 @@ object DatabaseModule {
                 MIGRATION_6_7,
                 MIGRATION_7_8,
                 MIGRATION_8_9,
+                MIGRATION_9_10,
             )
         // No destructive fallback: the migration chain is complete, and silently dropping the
         // accounts/credentials/mail tables would lose stored secrets. A missing migration should
@@ -100,5 +103,8 @@ object DatabaseModule {
     @Provides
     fun provideFolderDao(database: LibreMailDatabase): FolderDao = database.folderDao()
 
+    @Provides
+    fun provideSignatureDao(database: LibreMailDatabase): SignatureDao = database.signatureDao()
+
     private const val DB_NAME = "libremail.db"
 }
diff --git a/app/src/main/kotlin/org/libremail/domain/model/Draft.kt b/app/src/main/kotlin/org/libremail/domain/model/Draft.kt
index e6cecd9..29e1701 100644
--- a/app/src/main/kotlin/org/libremail/domain/model/Draft.kt
+++ b/app/src/main/kotlin/org/libremail/domain/model/Draft.kt
@@ -9,5 +9,7 @@ data class Draft(
     val subject: String,
     val body: String,
     val updatedAt: Long,
+    /** HTML form of [body] when the draft was composed with formatting; null for plaintext drafts. */
+    val bodyHtml: String? = null,
     val attachments: List<OutgoingAttachment> = emptyList(),
 )
diff --git a/app/src/main/kotlin/org/libremail/domain/model/OutboxMessage.kt b/app/src/main/kotlin/org/libremail/domain/model/OutboxMessage.kt
index bfa25bb..89104de 100644
--- a/app/src/main/kotlin/org/libremail/domain/model/OutboxMessage.kt
+++ b/app/src/main/kotlin/org/libremail/domain/model/OutboxMessage.kt
@@ -9,4 +9,6 @@ data class OutboxMessage(
     val body: String,
     val createdAt: Long,
     val lastError: String?,
+    /** HTML form of [body] when composed with formatting; null for plaintext messages. */
+    val bodyHtml: String? = null,
 )
diff --git a/app/src/main/kotlin/org/libremail/domain/model/OutgoingMessage.kt b/app/src/main/kotlin/org/libremail/domain/model/OutgoingMessage.kt
index 559720d..e8b70d6 100644
--- a/app/src/main/kotlin/org/libremail/domain/model/OutgoingMessage.kt
+++ b/app/src/main/kotlin/org/libremail/domain/model/OutgoingMessage.kt
@@ -1,13 +1,20 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 package org.libremail.domain.model
 
-/** A message the user is sending. [to]/[cc] are comma-separated address lists. */
+/**
+ * A message the user is sending. [to]/[cc] are comma-separated address lists.
+ *
+ * [body] is always the plain-text form. [bodyHtml] carries the HTML form when the message was
+ * composed with formatting; when it is null the message is sent as `text/plain` only (unchanged
+ * from the plaintext-only path), otherwise as `multipart/alternative` with both parts.
+ */
 data class OutgoingMessage(
     val accountId: String,
     val to: String,
     val cc: String = "",
     val subject: String,
     val body: String,
+    val bodyHtml: String? = null,
     val attachments: List<OutgoingAttachment> = emptyList(),
 )
 
diff --git a/app/src/main/kotlin/org/libremail/domain/model/Signature.kt b/app/src/main/kotlin/org/libremail/domain/model/Signature.kt
new file mode 100644
index 0000000..2537fab
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/domain/model/Signature.kt
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.domain.model
+
+import org.libremail.mail.HtmlToText
+
+/**
+ * A named, rich (HTML) email signature belonging to an account. Each account may have several; at
+ * most one is its [isDefault], which is the one auto-inserted when composing from that account.
+ */
+data class Signature(
+    val id: String,
+    val accountId: String,
+    val name: String,
+    /** The signature body as HTML (authored in the same rich editor as the message body). */
+    val html: String,
+    val isDefault: Boolean = false,
+) {
+    /** The signature as plain text, for the `text/plain` alternative and plaintext-only composing. */
+    fun plainText(): String = HtmlToText.convert(html)
+}
diff --git a/app/src/main/kotlin/org/libremail/mail/GraphSender.kt b/app/src/main/kotlin/org/libremail/mail/GraphSender.kt
index b583df4..6d42818 100644
--- a/app/src/main/kotlin/org/libremail/mail/GraphSender.kt
+++ b/app/src/main/kotlin/org/libremail/mail/GraphSender.kt
@@ -84,9 +84,16 @@ class GraphSender @Inject constructor() {
 
 /** Builds the Graph `sendMail` JSON body (a pure function, so it is unit-testable without a network). */
 internal fun buildSendMailPayload(message: OutgoingMessage, attachments: List<File>): String {
+    // Graph carries a single body object: send HTML when the message was formatted (Outlook renders
+    // it and derives its own plaintext), otherwise plain text so unformatted mail is unchanged.
+    val body = if (message.bodyHtml != null) {
+        JSONObject().put("contentType", "HTML").put("content", message.bodyHtml)
+    } else {
+        JSONObject().put("contentType", "Text").put("content", message.body)
+    }
     val mail = JSONObject()
         .put("subject", message.subject)
-        .put("body", JSONObject().put("contentType", "Text").put("content", message.body))
+        .put("body", body)
         .put("toRecipients", recipientsJson(message.to))
     if (message.cc.isNotBlank()) {
         mail.put("ccRecipients", recipientsJson(message.cc))
diff --git a/app/src/main/kotlin/org/libremail/mail/HtmlToText.kt b/app/src/main/kotlin/org/libremail/mail/HtmlToText.kt
new file mode 100644
index 0000000..b61f3d5
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/mail/HtmlToText.kt
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.mail
+
+/**
+ * Converts an HTML body into readable plain text for the `text/plain` alternative part and for
+ * quoting HTML originals in replies/forwards. Pure (no Android/Compose), so it is unit-testable on
+ * the JVM.
+ *
+ * It is intentionally lightweight — block elements become line breaks, list items gain a "• "
+ * marker, tags are dropped and entities decoded — rather than a full HTML renderer. The goal is a
+ * legible fallback, not a faithful reproduction.
+ */
+object HtmlToText {
+
+    private val BLOCK_BREAK = Regex(
+        "(?i)</?(p|div|tr|table|ul|ol|h[1-6]|blockquote)\\b[^>]*>|<br\\s*/?>",
+    )
+    private val LIST_ITEM = Regex("(?i)<li\\b[^>]*>")
+
+    fun convert(html: String): String {
+        var s = html
+        // Drop script/style contents outright so their text never leaks into the output.
+        s = s.replace(Regex("(?is)<(script|style)\\b[^>]*>.*?</\\1>"), "")
+        s = LIST_ITEM.replace(s, "\n• ")
+        s = BLOCK_BREAK.replace(s, "\n")
+        s = s.replace(Regex("<[^>]*>"), "")
+        s = decodeEntities(s)
+        // Collapse runs of spaces/tabs, then trim trailing spaces and cap consecutive blank lines.
+        s = s.replace(Regex("[ \\t]+"), " ")
+        s = s.lineSequence().joinToString("\n") { it.trim() }
+        s = s.replace(Regex("\n{3,}"), "\n\n")
+        return s.trim()
+    }
+
+    private fun decodeEntities(s: String): String = s
+        .replace("&nbsp;", " ")
+        .replace("&lt;", "<")
+        .replace("&gt;", ">")
+        .replace("&quot;", "\"")
+        .replace("&#39;", "'")
+        .replace("&apos;", "'")
+        .replace("&mdash;", "—")
+        .replace("&ndash;", "–")
+        .replace("&amp;", "&")
+}
diff --git a/app/src/main/kotlin/org/libremail/mail/SmtpSender.kt b/app/src/main/kotlin/org/libremail/mail/SmtpSender.kt
index b034896..f243029 100644
--- a/app/src/main/kotlin/org/libremail/mail/SmtpSender.kt
+++ b/app/src/main/kotlin/org/libremail/mail/SmtpSender.kt
@@ -7,6 +7,7 @@ import jakarta.mail.internet.InternetAddress
 import jakarta.mail.internet.MimeBodyPart
 import jakarta.mail.internet.MimeMessage
 import jakarta.mail.internet.MimeMultipart
+import jakarta.mail.internet.MimePart
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import org.libremail.domain.model.MailSecurity
@@ -62,16 +63,7 @@ class SmtpSender @Inject constructor() {
             subject = message.subject
             sentDate = Date()
         }
-        if (attachments.isEmpty()) {
-            mime.setText(message.body, "UTF-8")
-        } else {
-            val multipart = MimeMultipart()
-            multipart.addBodyPart(MimeBodyPart().apply { setText(message.body, "UTF-8") })
-            attachments.forEach { file ->
-                multipart.addBodyPart(MimeBodyPart().apply { attachFile(file) })
-            }
-            mime.setContent(multipart)
-        }
+        applyBody(mime, message, attachments)
 
         val transport = session.getTransport(protocol)
         transport.connect(params.host, params.port, params.username, params.secret)
@@ -82,6 +74,40 @@ class SmtpSender @Inject constructor() {
         }
     }
 
+    /**
+     * Sets the message body:
+     *  - plaintext-only ([OutgoingMessage.bodyHtml] null): a single `text/plain` part, exactly as
+     *    before, so unformatted mail is unchanged on the wire;
+     *  - formatted: a `multipart/alternative` of `text/plain` (fallback, first) + `text/html`
+     *    (preferred, last, per RFC 2046).
+     * When there are attachments the body is nested inside a `multipart/mixed` as its first part.
+     */
+    private fun applyBody(mime: MimeMessage, message: OutgoingMessage, attachments: List<File>) {
+        if (attachments.isEmpty()) {
+            setBody(mime, message)
+            return
+        }
+        val mixed = MimeMultipart("mixed")
+        mixed.addBodyPart(MimeBodyPart().also { setBody(it, message) })
+        attachments.forEach { file -> mixed.addBodyPart(MimeBodyPart().apply { attachFile(file) }) }
+        mime.setContent(mixed)
+    }
+
+    /** Writes the body onto [part]: plain text, or a text/plain + text/html alternative when formatted. */
+    private fun setBody(part: MimePart, message: OutgoingMessage) {
+        val html = message.bodyHtml
+        if (html == null) {
+            part.setText(message.body, "UTF-8")
+        } else {
+            part.setContent(alternative(message.body, html))
+        }
+    }
+
+    private fun alternative(plain: String, html: String): MimeMultipart = MimeMultipart("alternative").apply {
+        addBodyPart(MimeBodyPart().apply { setText(plain, "UTF-8") })
+        addBodyPart(MimeBodyPart().apply { setContent(html, "text/html; charset=UTF-8") })
+    }
+
     private companion object {
         const val TIMEOUT_MS = "15000"
     }
diff --git a/app/src/main/kotlin/org/libremail/richtext/RichText.kt b/app/src/main/kotlin/org/libremail/richtext/RichText.kt
new file mode 100644
index 0000000..923ee13
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/richtext/RichText.kt
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.richtext
+
+/** Inline character styles the compose editor supports. */
+enum class RichStyle { BOLD, ITALIC, UNDERLINE }
+
+/** A run of [style] over the half-open range [[start], [end]) of the plain text. */
+data class RichSpan(val start: Int, val end: Int, val style: RichStyle)
+
+/** A hyperlink over the half-open range [[start], [end]) pointing at [url]. */
+data class RichLink(val start: Int, val end: Int, val url: String)
+
+/**
+ * The compose editor's internal rich-text model: plain [text] plus inline [spans] and [links].
+ *
+ * Block structure (unordered/ordered lists and block quotes) is encoded as recognizable line
+ * prefixes inside [text] — "• " for bullets, "N. " for numbered items, and "> " for quotes — so
+ * the editor can stay a single plain-text field (keeping the plaintext-only experience smooth)
+ * while the model still round-trips cleanly to real HTML and to a readable plaintext fallback.
+ */
+data class RichTextContent(
+    val text: String = "",
+    val spans: List<RichSpan> = emptyList(),
+    val links: List<RichLink> = emptyList(),
+) {
+    val isBlank: Boolean get() = text.isBlank()
+
+    /**
+     * True when the content carries anything a plaintext field could not represent: inline styling,
+     * a link, or a block marker. When false, callers should send/persist plaintext only so an
+     * unformatted message stays byte-for-byte identical to the old plaintext-only path.
+     */
+    fun hasFormatting(): Boolean =
+        spans.isNotEmpty() || links.isNotEmpty() || text.lineSequence().any { lineMarker(it) != null }
+}
+
+/** Recognized block markers and the tags they map to. */
+internal const val BULLET_PREFIX = "• "
+internal const val QUOTE_PREFIX = "> "
+private val ORDERED_PREFIX = Regex("^\\d+\\. ")
+
+private enum class Kind { PARAGRAPH, BULLET, ORDERED, QUOTE }
+
+private data class Line(val kind: Kind, val contentStart: Int, val contentEnd: Int)
+
+/** The block marker prefixing [line], or null for an ordinary paragraph line. */
+internal fun lineMarker(line: String): String? = when {
+    line.startsWith(BULLET_PREFIX) -> BULLET_PREFIX
+    line.startsWith(QUOTE_PREFIX) -> QUOTE_PREFIX
+    else -> ORDERED_PREFIX.find(line)?.value
+}
+
+/**
+ * Serializes [RichTextContent] to a small, email-safe HTML subset and back. Pure (no Android or
+ * Compose types), so the whole conversion is unit-testable on the JVM.
+ *
+ * The emitted subset — `<b> <i> <u> <a> <ul>/<ol>/<li> <blockquote> <br>` — is deliberately narrow
+ * so [fromHtml] is a faithful inverse for anything [toHtml] produces (drafts round-trip losslessly).
+ */
+object RichTextHtml {
+
+    fun toHtml(content: RichTextContent): String {
+        if (content.text.isEmpty()) return ""
+        val lines = classify(content.text)
+        val sb = StringBuilder()
+        var i = 0
+        while (i < lines.size) {
+            i = when (lines[i].kind) {
+                Kind.BULLET -> emitList(sb, content, lines, i, Kind.BULLET, "ul")
+                Kind.ORDERED -> emitList(sb, content, lines, i, Kind.ORDERED, "ol")
+                Kind.QUOTE -> emitQuote(sb, content, lines, i)
+                Kind.PARAGRAPH -> emitParagraph(sb, content, lines, i)
+            }
+        }
+        return sb.toString()
+    }
+
+    /** A readable plaintext rendering — the model's [RichTextContent.text] already carries markers. */
+    fun toPlainText(content: RichTextContent): String = content.text
+
+    fun fromHtml(html: String): RichTextContent = HtmlToRichParser(html).parse()
+}
+
+private fun classify(text: String): List<Line> {
+    val lines = ArrayList<Line>()
+    var start = 0
+    while (true) {
+        val nl = text.indexOf('\n', start)
+        val end = if (nl == -1) text.length else nl
+        val marker = lineMarker(text.substring(start, end))
+        val kind = when (marker) {
+            BULLET_PREFIX -> Kind.BULLET
+            QUOTE_PREFIX -> Kind.QUOTE
+            null -> Kind.PARAGRAPH
+            else -> Kind.ORDERED
+        }
+        lines.add(Line(kind, start + (marker?.length ?: 0), end))
+        if (nl == -1) break
+        start = nl + 1
+    }
+    return lines
+}
+
+private fun emitList(
+    sb: StringBuilder,
+    content: RichTextContent,
+    lines: List<Line>,
+    from: Int,
+    kind: Kind,
+    tag: String,
+): Int {
+    sb.append("<").append(tag).append(">")
+    var i = from
+    while (i < lines.size && lines[i].kind == kind) {
+        sb.append("<li>").append(renderInline(content, lines[i].contentStart, lines[i].contentEnd)).append("</li>")
+        i++
+    }
+    sb.append("</").append(tag).append(">")
+    return i
+}
+
+private fun emitQuote(sb: StringBuilder, content: RichTextContent, lines: List<Line>, from: Int): Int {
+    sb.append("<blockquote>")
+    var i = from
+    while (i < lines.size && lines[i].kind == Kind.QUOTE) {
+        if (i > from) sb.append("<br>")
+        sb.append(renderInline(content, lines[i].contentStart, lines[i].contentEnd))
+        i++
+    }
+    sb.append("</blockquote>")
+    return i
+}
+
+private fun emitParagraph(sb: StringBuilder, content: RichTextContent, lines: List<Line>, from: Int): Int {
+    sb.append("<p>")
+    var i = from
+    while (i < lines.size && lines[i].kind == Kind.PARAGRAPH) {
+        if (i > from) sb.append("<br>")
+        sb.append(renderInline(content, lines[i].contentStart, lines[i].contentEnd))
+        i++
+    }
+    sb.append("</p>")
+    return i
+}
+
+/** Renders the inline styling/links over [[from], [to]) as nested `<a>/<b>/<i>/<u>` tags. */
+private fun renderInline(content: RichTextContent, from: Int, to: Int): String {
+    if (from >= to) return ""
+    val points = cutPoints(content, from, to)
+    val sb = StringBuilder()
+    for (idx in 0 until points.size - 1) {
+        val a = points[idx]
+        val b = points[idx + 1]
+        if (a < b) appendRun(sb, content, a, b)
+    }
+    return sb.toString()
+}
+
+/** The sorted set of offsets where a span or link starts/ends within [[from], [to]]. */
+private fun cutPoints(content: RichTextContent, from: Int, to: Int): List<Int> {
+    val cuts = sortedSetOf(from, to)
+    fun add(start: Int, end: Int) {
+        if (end > from && start < to) {
+            cuts.add(start.coerceIn(from, to))
+            cuts.add(end.coerceIn(from, to))
+        }
+    }
+    content.spans.forEach { add(it.start, it.end) }
+    content.links.forEach { add(it.start, it.end) }
+    return cuts.toList()
+}
+
+/** Emits one constant-styling run [[a], [b]) with fully-closed tags, so nesting is always valid. */
+private fun appendRun(sb: StringBuilder, content: RichTextContent, a: Int, b: Int) {
+    val styles = content.spans.filter { it.start <= a && b <= it.end }.map { it.style }.toSet()
+    val link = content.links.firstOrNull { it.start <= a && b <= it.end }
+    if (link != null) sb.append("<a href=\"").append(escapeAttr(link.url)).append("\">")
+    if (RichStyle.BOLD in styles) sb.append("<b>")
+    if (RichStyle.ITALIC in styles) sb.append("<i>")
+    if (RichStyle.UNDERLINE in styles) sb.append("<u>")
+    sb.append(escape(content.text.substring(a, b)))
+    if (RichStyle.UNDERLINE in styles) sb.append("</u>")
+    if (RichStyle.ITALIC in styles) sb.append("</i>")
+    if (RichStyle.BOLD in styles) sb.append("</b>")
+    if (link != null) sb.append("</a>")
+}
+
+/**
+ * Parses the narrow HTML subset [toHtml][RichTextHtml.toHtml] emits (plus `strong`/`em` and
+ * pretty-printer whitespace) back into a [RichTextContent]. A small state machine keeps the nesting
+ * shallow: [handleTag] dispatches to one-liner helpers and [handleText] appends decoded text.
+ */
+private class HtmlToRichParser(private val html: String) {
+    private val text = StringBuilder()
+    private val spans = ArrayList<RichSpan>()
+    private val links = ArrayList<RichLink>()
+    private var boldStart = -1
+    private var italicStart = -1
+    private var underlineStart = -1
+    private var linkStart = -1
+    private var linkUrl = ""
+    private var listType: Char? = null
+    private var olCount = 0
+    private var inQuote = false
+
+    fun parse(): RichTextContent {
+        var i = 0
+        while (i < html.length) {
+            if (html[i] == '<') {
+                val gt = html.indexOf('>', i)
+                if (gt == -1) break
+                handleTag(html.substring(i + 1, gt).trim())
+                i = gt + 1
+            } else {
+                val lt = html.indexOf('<', i)
+                val end = if (lt == -1) html.length else lt
+                handleText(html.substring(i, end))
+                i = end
+            }
+        }
+        return finish()
+    }
+
+    private fun atLineStart() = text.isEmpty() || text.last() == '\n'
+
+    private fun newlineIfNeeded() {
+        if (!atLineStart()) text.append('\n')
+    }
+
+    private fun handleTag(raw: String) {
+        val closing = raw.startsWith("/")
+        val body = raw.removePrefix("/").trim()
+        when (body.substringBefore(' ').substringBefore('/').lowercase()) {
+            "br" -> {
+                text.append('\n')
+                if (inQuote) text.append(QUOTE_PREFIX)
+            }
+            "b", "strong" -> boldStart = toggle(closing, boldStart, RichStyle.BOLD)
+            "i", "em" -> italicStart = toggle(closing, italicStart, RichStyle.ITALIC)
+            "u" -> underlineStart = toggle(closing, underlineStart, RichStyle.UNDERLINE)
+            "a" -> handleAnchor(closing, body)
+            "ul" -> handleList(closing, 'u')
+            "ol" -> handleList(closing, 'o')
+            "li" -> if (!closing) startListItem()
+            "blockquote" -> handleQuote(closing)
+            "p", "div" -> newlineIfNeeded()
+            else -> Unit
+        }
+    }
+
+    /** Opens a style (returns the current offset) or closes it (records the span, returns -1). */
+    private fun toggle(closing: Boolean, openOffset: Int, style: RichStyle): Int {
+        if (!closing) return text.length
+        if (openOffset >= 0) spans.add(RichSpan(openOffset, text.length, style))
+        return -1
+    }
+
+    private fun handleAnchor(closing: Boolean, body: String) {
+        if (closing) {
+            if (linkStart >= 0) {
+                links.add(RichLink(linkStart, text.length, linkUrl))
+                linkStart = -1
+                linkUrl = ""
+            }
+        } else {
+            linkStart = text.length
+            linkUrl = extractHref(body)
+        }
+    }
+
+    private fun handleList(closing: Boolean, type: Char) {
+        if (closing) {
+            listType = null
+        } else {
+            listType = type
+            if (type == 'o') olCount = 0
+        }
+        newlineIfNeeded()
+    }
+
+    private fun startListItem() {
+        newlineIfNeeded()
+        if (listType == 'o') {
+            olCount++
+            text.append("$olCount. ")
+        } else {
+            text.append(BULLET_PREFIX)
+        }
+    }
+
+    private fun handleQuote(closing: Boolean) {
+        newlineIfNeeded()
+        inQuote = !closing
+        if (!closing) text.append(QUOTE_PREFIX)
+    }
+
+    private fun handleText(chunk: String) {
+        // Drop the insignificant whitespace a pretty-printer leaves between block tags (blank runs at
+        // a line start, or any blank run with a newline), but keep a real space between inline runs.
+        if (!(chunk.isBlank() && (atLineStart() || chunk.contains('\n')))) text.append(unescape(chunk))
+    }
+
+    private fun finish(): RichTextContent {
+        val out = text.toString().trimEnd('\n')
+        val len = out.length
+        if (boldStart in 0 until len) spans.add(RichSpan(boldStart, len, RichStyle.BOLD))
+        if (italicStart in 0 until len) spans.add(RichSpan(italicStart, len, RichStyle.ITALIC))
+        if (underlineStart in 0 until len) spans.add(RichSpan(underlineStart, len, RichStyle.UNDERLINE))
+        if (linkStart in 0 until len) links.add(RichLink(linkStart, len, linkUrl))
+        return RichTextContent(
+            text = out,
+            spans = spans.filter { it.end <= len && it.start < it.end },
+            links = links.filter { it.end <= len && it.start < it.end },
+        )
+    }
+}
+
+private fun extractHref(tagBody: String): String {
+    val match = Regex("href\\s*=\\s*(?:\"([^\"]*)\"|'([^']*)')", RegexOption.IGNORE_CASE).find(tagBody) ?: return ""
+    val (doubleQuoted, singleQuoted) = match.destructured
+    return unescape(doubleQuoted.ifEmpty { singleQuoted })
+}
+
+private fun escape(s: String): String = s.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
+
+private fun escapeAttr(s: String): String = escape(s).replace("\"", "&quot;")
+
+private fun unescape(s: String): String = s
+    .replace("&lt;", "<")
+    .replace("&gt;", ">")
+    .replace("&quot;", "\"")
+    .replace("&#39;", "'")
+    .replace("&apos;", "'")
+    .replace("&nbsp;", " ")
+    .replace("&amp;", "&")
diff --git a/app/src/main/kotlin/org/libremail/richtext/RichTextEditing.kt b/app/src/main/kotlin/org/libremail/richtext/RichTextEditing.kt
new file mode 100644
index 0000000..0e7a149
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/richtext/RichTextEditing.kt
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.richtext
+
+/** A block-level marker the toolbar can toggle over the selected lines. */
+enum class BlockMarker { BULLET, ORDERED, QUOTE }
+
+/** The result of an editing op: the new [content] and where the selection should land. */
+data class EditResult(val content: RichTextContent, val selectionStart: Int, val selectionEnd: Int)
+
+/**
+ * Pure editing operations over [RichTextContent] — toggling inline styles/links and block markers —
+ * shared by the Compose editor's toolbar. Keeping them free of Compose types makes the tricky index
+ * bookkeeping (splitting spans, shifting offsets when a line marker is inserted/removed) unit-testable
+ * on the JVM.
+ */
+object RichTextEditing {
+
+    /** Adds [style] over [[start], [end]) if it is not already fully styled, otherwise removes it. */
+    fun toggleStyle(content: RichTextContent, start: Int, end: Int, style: RichStyle): RichTextContent {
+        if (start >= end) return content
+        val others = content.spans.filter { it.style != style }
+        val same = content.spans.filter { it.style == style }
+        val updated = if (isFullyStyled(same, start, end)) {
+            subtractRange(same, start, end)
+        } else {
+            mergeSameStyle(same + RichSpan(start, end, style))
+        }
+        return content.copy(spans = (others + updated).sortedBy { it.start })
+    }
+
+    /** Links [[start], [end]) to [url], replacing any links that overlap the range. */
+    fun applyLink(content: RichTextContent, start: Int, end: Int, url: String): RichTextContent {
+        if (start >= end || url.isBlank()) return content
+        val kept = content.links.filter { it.end <= start || it.start >= end }
+        return content.copy(links = (kept + RichLink(start, end, url)).sortedBy { it.start })
+    }
+
+    /** Removes any links overlapping [[start], [end]). */
+    fun removeLink(content: RichTextContent, start: Int, end: Int): RichTextContent {
+        if (start >= end) return content
+        return content.copy(links = content.links.filter { it.end <= start || it.start >= end })
+    }
+
+    /** Whether [[start], [end]) is entirely covered by [style] (drives the toolbar's toggle state). */
+    fun isStyled(content: RichTextContent, start: Int, end: Int, style: RichStyle): Boolean =
+        start < end && isFullyStyled(content.spans.filter { it.style == style }, start, end)
+
+    /** Whether every line the selection touches carries [marker]. */
+    fun hasBlock(content: RichTextContent, start: Int, end: Int, marker: BlockMarker): Boolean {
+        val lineStarts = lineStartsTouching(content.text, start, end)
+        return lineStarts.isNotEmpty() && lineStarts.all { markerAt(content.text, it) == marker }
+    }
+
+    /**
+     * Toggles [marker] across every line the selection touches: if all those lines already carry it,
+     * it is removed; otherwise it is applied (replacing any other block marker already there). Spans,
+     * links and the selection are shifted to track the inserted/removed prefixes.
+     */
+    fun toggleBlock(content: RichTextContent, start: Int, end: Int, marker: BlockMarker): EditResult {
+        val text = content.text
+        val lineStarts = lineStartsTouching(text, start, end)
+        val allHaveMarker = lineStarts.all { markerAt(text, it) == marker }
+        val edits = ArrayList<LineEdit>()
+        var ordinal = 1
+        for (lineStart in lineStarts) {
+            val existing = markerLengthAt(text, lineStart)
+            when {
+                allHaveMarker && existing > 0 -> edits.add(LineEdit(lineStart, existing, ""))
+                allHaveMarker -> Unit
+                else -> edits.add(LineEdit(lineStart, existing, insertFor(marker, ordinal++)))
+            }
+        }
+        val (newText, remap) = applyEdits(text, edits)
+        val newSpans = content.spans.mapNotNull { remapSpan(it, remap) }
+        val newLinks = content.links.mapNotNull { remapLink(it, remap) }
+        return EditResult(RichTextContent(newText, newSpans, newLinks), remap(start), remap(end))
+    }
+}
+
+private fun insertFor(marker: BlockMarker, ordinal: Int): String = when (marker) {
+    BlockMarker.BULLET -> BULLET_PREFIX
+    BlockMarker.QUOTE -> QUOTE_PREFIX
+    BlockMarker.ORDERED -> "$ordinal. "
+}
+
+private fun remapSpan(span: RichSpan, remap: (Int) -> Int): RichSpan? {
+    val s = remap(span.start)
+    val e = remap(span.end)
+    return if (s < e) RichSpan(s, e, span.style) else null
+}
+
+private fun remapLink(link: RichLink, remap: (Int) -> Int): RichLink? {
+    val s = remap(link.start)
+    val e = remap(link.end)
+    return if (s < e) RichLink(s, e, link.url) else null
+}
+
+// --- inline style helpers ---
+
+private fun isFullyStyled(spans: List<RichSpan>, start: Int, end: Int): Boolean {
+    var pos = start
+    for (span in spans.filter { it.end > start && it.start < end }.sortedBy { it.start }) {
+        if (span.start > pos) return false
+        pos = maxOf(pos, span.end)
+        if (pos >= end) return true
+    }
+    return pos >= end
+}
+
+private fun subtractRange(spans: List<RichSpan>, start: Int, end: Int): List<RichSpan> = spans.flatMap { span ->
+    when {
+        span.end <= start || span.start >= end -> listOf(span)
+        else -> buildList {
+            if (span.start < start) add(span.copy(end = start))
+            if (span.end > end) add(span.copy(start = end))
+        }
+    }
+}
+
+private fun mergeSameStyle(spans: List<RichSpan>): List<RichSpan> {
+    val merged = ArrayList<RichSpan>()
+    for (span in spans.sortedBy { it.start }) {
+        val last = merged.lastOrNull()
+        if (last != null && span.start <= last.end) {
+            merged[merged.size - 1] = last.copy(end = maxOf(last.end, span.end))
+        } else {
+            merged.add(span)
+        }
+    }
+    return merged
+}
+
+// --- block marker helpers ---
+
+private val ORDERED = Regex("^\\d+\\. ")
+
+private fun markerAt(text: String, lineStart: Int): BlockMarker? {
+    val rest = text.substring(lineStart)
+    return when {
+        rest.startsWith(BULLET_PREFIX) -> BlockMarker.BULLET
+        rest.startsWith(QUOTE_PREFIX) -> BlockMarker.QUOTE
+        // ORDERED is anchored at ^, so find() matches only when this line starts with "N. ".
+        ORDERED.find(rest) != null -> BlockMarker.ORDERED
+        else -> null
+    }
+}
+
+private fun markerLengthAt(text: String, lineStart: Int): Int {
+    val rest = text.substring(lineStart)
+    return when {
+        rest.startsWith(BULLET_PREFIX) -> BULLET_PREFIX.length
+        rest.startsWith(QUOTE_PREFIX) -> QUOTE_PREFIX.length
+        else -> ORDERED.find(rest)?.value?.length ?: 0
+    }
+}
+
+/** Start offsets of every line the range [[start], [end]] intersects (a caret counts as its line). */
+private fun lineStartsTouching(text: String, start: Int, end: Int): List<Int> {
+    val from = start.coerceIn(0, text.length)
+    val to = end.coerceIn(from, text.length)
+    val result = ArrayList<Int>()
+    var lineStart = if (from == 0) 0 else text.lastIndexOf('\n', from - 1).let { if (it == -1) 0 else it + 1 }
+    while (lineStart <= text.length) {
+        result.add(lineStart)
+        val nl = text.indexOf('\n', lineStart)
+        if (nl == -1 || nl >= to) break
+        lineStart = nl + 1
+    }
+    return result
+}
+
+private data class LineEdit(val offset: Int, val deleteLen: Int, val insert: String)
+
+/** Applies line-start [edits] (ascending, non-overlapping) and returns the new text + an index remap. */
+private fun applyEdits(text: String, edits: List<LineEdit>): Pair<String, (Int) -> Int> {
+    if (edits.isEmpty()) return text to { it }
+    val sorted = edits.sortedBy { it.offset }
+    val sb = StringBuilder()
+    var cursor = 0
+    for (edit in sorted) {
+        sb.append(text, cursor, edit.offset)
+        sb.append(edit.insert)
+        cursor = edit.offset + edit.deleteLen
+    }
+    sb.append(text, cursor, text.length)
+    val remap: (Int) -> Int = { index -> remapIndex(index, sorted).coerceIn(0, sb.length) }
+    return sb.toString() to remap
+}
+
+private fun remapIndex(index: Int, edits: List<LineEdit>): Int {
+    var delta = 0
+    for (edit in edits) {
+        val delEnd = edit.offset + edit.deleteLen
+        when {
+            delEnd <= index -> delta += edit.insert.length - edit.deleteLen
+            edit.offset < index -> delta += edit.insert.length - (index - edit.offset)
+        }
+    }
+    return index + delta
+}
diff --git a/app/src/main/kotlin/org/libremail/ui/LibreMailApp.kt b/app/src/main/kotlin/org/libremail/ui/LibreMailApp.kt
index 0301b0f..5ac1e12 100644
--- a/app/src/main/kotlin/org/libremail/ui/LibreMailApp.kt
+++ b/app/src/main/kotlin/org/libremail/ui/LibreMailApp.kt
@@ -24,6 +24,8 @@ import org.libremail.ui.outbox.OutboxScreen
 import org.libremail.ui.reader.ReaderScreen
 import org.libremail.ui.settings.AccountSettingsScreen
 import org.libremail.ui.settings.SettingsScreen
+import org.libremail.ui.settings.SignatureEditScreen
+import org.libremail.ui.settings.SignaturesScreen
 
 @Composable
 fun LibreMailApp() {
@@ -86,8 +88,35 @@ fun LibreMailApp() {
         composable(
             route = Routes.ACCOUNT_SETTINGS_PATTERN,
             arguments = listOf(navArgument(Routes.ACCOUNT_SETTINGS_ARG_ID) { type = NavType.StringType }),
+        ) { backStackEntry ->
+            val accountId = backStackEntry.arguments?.getString(Routes.ACCOUNT_SETTINGS_ARG_ID).orEmpty()
+            AccountSettingsScreen(
+                onBack = navController::popBackStack,
+                onManageSignatures = { navController.navigate(Routes.signatures(accountId)) },
+            )
+        }
+        composable(
+            route = Routes.SIGNATURES_PATTERN,
+            arguments = listOf(navArgument(Routes.SIGNATURES_ARG_ACCOUNT) { type = NavType.StringType }),
+        ) { backStackEntry ->
+            val accountId = backStackEntry.arguments?.getString(Routes.SIGNATURES_ARG_ACCOUNT).orEmpty()
+            SignaturesScreen(
+                onBack = navController::popBackStack,
+                onEdit = { signatureId -> navController.navigate(Routes.signatureEdit(accountId, signatureId)) },
+                onAdd = { navController.navigate(Routes.signatureEdit(accountId)) },
+            )
+        }
+        composable(
+            route = Routes.SIGNATURE_EDIT_PATTERN,
+            arguments = listOf(
+                navArgument(Routes.SIGNATURE_EDIT_ARG_ACCOUNT) { type = NavType.StringType },
+                navArgument(Routes.SIGNATURE_EDIT_ARG_ID) {
+                    type = NavType.StringType
+                    defaultValue = ""
+                },
+            ),
         ) {
-            AccountSettingsScreen(onBack = navController::popBackStack)
+            SignatureEditScreen(onBack = navController::popBackStack)
         }
         composable(Routes.ACCOUNT_SETUP) {
             AccountSetupScreen(
diff --git a/app/src/main/kotlin/org/libremail/ui/compose/ComposeScreen.kt b/app/src/main/kotlin/org/libremail/ui/compose/ComposeScreen.kt
index 50e748b..9c229d5 100644
--- a/app/src/main/kotlin/org/libremail/ui/compose/ComposeScreen.kt
+++ b/app/src/main/kotlin/org/libremail/ui/compose/ComposeScreen.kt
@@ -145,6 +145,7 @@ fun ComposeScreen(onBack: () -> Unit, viewModel: ComposeViewModel = hiltViewMode
                     label = { Text(stringResource(R.string.compose_to)) },
                     singleLine = true,
                     keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Email),
+                    shape = MaterialTheme.shapes.medium,
                     modifier = Modifier.fillMaxWidth(),
                 )
                 if (state.suggestions.isNotEmpty()) {
@@ -158,6 +159,7 @@ fun ComposeScreen(onBack: () -> Unit, viewModel: ComposeViewModel = hiltViewMode
                     label = { Text(stringResource(R.string.compose_cc)) },
                     singleLine = true,
                     keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Email),
+                    shape = MaterialTheme.shapes.medium,
                     modifier = Modifier.fillMaxWidth(),
                 )
                 Spacer(Modifier.height(8.dp))
@@ -166,6 +168,7 @@ fun ComposeScreen(onBack: () -> Unit, viewModel: ComposeViewModel = hiltViewMode
                     onValueChange = viewModel::onSubjectChange,
                     label = { Text(stringResource(R.string.compose_subject)) },
                     singleLine = true,
+                    shape = MaterialTheme.shapes.medium,
                     modifier = Modifier.fillMaxWidth(),
                 )
                 AttachmentsSection(
@@ -174,10 +177,11 @@ fun ComposeScreen(onBack: () -> Unit, viewModel: ComposeViewModel = hiltViewMode
                     onRemove = viewModel::removeAttachment,
                 )
                 Spacer(Modifier.height(8.dp))
-                OutlinedTextField(
-                    value = state.body,
-                    onValueChange = viewModel::onBodyChange,
-                    label = { Text(stringResource(R.string.compose_body)) },
+                RichTextBodyField(
+                    body = state.body,
+                    bodyHtml = state.bodyHtml,
+                    onBodyChange = viewModel::onBodyChange,
+                    label = stringResource(R.string.compose_body),
                     modifier = Modifier.fillMaxWidth().weight(1f),
                 )
             }
diff --git a/app/src/main/kotlin/org/libremail/ui/compose/ComposeViewModel.kt b/app/src/main/kotlin/org/libremail/ui/compose/ComposeViewModel.kt
index d37ca90..cc6a796 100644
--- a/app/src/main/kotlin/org/libremail/ui/compose/ComposeViewModel.kt
+++ b/app/src/main/kotlin/org/libremail/ui/compose/ComposeViewModel.kt
@@ -18,13 +18,17 @@ import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import org.libremail.contacts.ContactSuggestion
 import org.libremail.contacts.ContactsRepository
+import org.libremail.data.SignatureBlock
 import org.libremail.data.settings.AccountSettingsRepository
+import org.libremail.data.settings.SignatureRepository
 import org.libremail.domain.model.Account
 import org.libremail.domain.model.Draft
 import org.libremail.domain.model.OutgoingAttachment
 import org.libremail.domain.model.OutgoingMessage
 import org.libremail.domain.repository.AccountRepository
 import org.libremail.domain.repository.MailRepository
+import org.libremail.richtext.RichTextContent
+import org.libremail.richtext.RichTextHtml
 import org.libremail.ui.navigation.Routes
 import java.util.UUID
 import javax.inject.Inject
@@ -33,7 +37,10 @@ data class ComposeUiState(
     val to: String = "",
     val cc: String = "",
     val subject: String = "",
+    /** The plaintext form of the body (also the `text/plain` fallback when sending). */
     val body: String = "",
+    /** The HTML form of the body, or null when the message carries no formatting (plaintext-only). */
+    val bodyHtml: String? = null,
     val fromAccountId: String? = null,
     val attachments: List<OutgoingAttachment> = emptyList(),
     val suggestions: List<ContactSuggestion> = emptyList(),
@@ -49,6 +56,7 @@ class ComposeViewModel @Inject constructor(
     private val accountRepository: AccountRepository,
     private val contactsRepository: ContactsRepository,
     private val accountSettingsRepository: AccountSettingsRepository,
+    private val signatureRepository: SignatureRepository,
 ) : ViewModel() {
 
     private val draftId: String? =
@@ -76,7 +84,7 @@ class ComposeViewModel @Inject constructor(
     @Volatile private var navigated = false
 
     /** The signature block last appended to the body, so a From-change can swap it out cleanly. */
-    private var appliedSignatureBlock = ""
+    private var appliedSignatureBlock = SignatureBlock.EMPTY
 
     init {
         if (draftId != null) {
@@ -88,6 +96,7 @@ class ComposeViewModel @Inject constructor(
                             cc = draft.cc,
                             subject = draft.subject,
                             body = draft.body,
+                            bodyHtml = draft.bodyHtml,
                             fromAccountId = draft.accountId ?: it.fromAccountId,
                             attachments = draft.attachments,
                         )
@@ -112,27 +121,63 @@ class ComposeViewModel @Inject constructor(
 
     fun onCcChange(value: String) = _state.update { it.copy(cc = value) }
     fun onSubjectChange(value: String) = _state.update { it.copy(subject = value) }
-    fun onBodyChange(value: String) = _state.update { it.copy(body = value) }
+
+    /**
+     * The rich editor reports the current body in both forms: [plain] (also the plaintext fallback)
+     * and [html], which is null when the content carries no formatting so the message stays
+     * plaintext-only. Both are held for sending and for saving the draft.
+     */
+    fun onBodyChange(plain: String, html: String?) = _state.update { it.copy(body = plain, bodyHtml = html) }
+
     fun selectFrom(accountId: String) {
         viewModelScope.launch { applySignature(accountId) }
     }
 
     /**
-     * Sets the sending account and swaps its signature into the body: strips the previously-appended
-     * signature block (when the body still ends with it) and appends the newly-selected account's.
+     * Sets the sending account and swaps its default signature into the body: strips the
+     * previously-appended block (when the body still ends with it) and appends the newly-selected
+     * account's, in both the plaintext and HTML representations. Honors the account's
+     * "append signature" preference.
      */
     private suspend fun applySignature(accountId: String) {
-        val block = accountSettingsRepository.get(accountId).signatureBlock()
+        val settings = accountSettingsRepository.get(accountId)
+        val block = if (settings.signatureEnabled) {
+            SignatureBlock.of(signatureRepository.getDefault(accountId))
+        } else {
+            SignatureBlock.EMPTY
+        }
         _state.update { s ->
-            val base = if (appliedSignatureBlock.isNotEmpty() && s.body.endsWith(appliedSignatureBlock)) {
-                s.body.removeSuffix(appliedSignatureBlock)
-            } else {
-                s.body
-            }
-            s.copy(fromAccountId = accountId, body = base + block)
+            val basePlain = s.body.stripSuffixIfPresent(appliedSignatureBlock.plain)
+            val newBody = basePlain + block.plain
+            s.copy(fromAccountId = accountId, body = newBody, bodyHtml = swapHtmlSignature(s.bodyHtml, newBody, block))
         }
         appliedSignatureBlock = block
     }
+
+    /**
+     * Swaps the signature in the HTML body. When the old block is still a clean suffix (the common
+     * case — the user changed accounts before editing), it is stripped and the new one appended,
+     * preserving any formatting the user applied. Otherwise the HTML was re-serialized after editing
+     * and no longer ends with the old block, so it is rebuilt from the plaintext to avoid ever
+     * duplicating the signature (inline styling from before the switch is not preserved in that case).
+     */
+    private fun swapHtmlSignature(currentHtml: String?, newBody: String, block: SignatureBlock): String? {
+        val old = appliedSignatureBlock.html
+        val cleanlyStrippable = old.isEmpty() || currentHtml == null || currentHtml.endsWith(old)
+        val combined = if (cleanlyStrippable) {
+            (currentHtml?.removeSuffix(old) ?: "") + block.html
+        } else {
+            RichTextHtml.toHtml(RichTextContent(newBody))
+        }
+        return normalizedHtml(combined)
+    }
+
+    private fun String.stripSuffixIfPresent(suffix: String): String =
+        if (suffix.isNotEmpty() && endsWith(suffix)) removeSuffix(suffix) else this
+
+    /** Keeps an HTML body only when it actually carries formatting, so plaintext stays plaintext. */
+    private fun normalizedHtml(html: String): String? =
+        if (html.isBlank() || !RichTextHtml.fromHtml(html).hasFormatting()) null else html
     fun addAttachments(items: List<OutgoingAttachment>) =
         _state.update { it.copy(attachments = it.attachments + items) }
     fun removeAttachment(uri: String) = _state.update {
@@ -200,6 +245,7 @@ class ComposeViewModel @Inject constructor(
                     subject = s.subject,
                     body = s.body,
                     updatedAt = System.currentTimeMillis(),
+                    bodyHtml = s.bodyHtml,
                     attachments = s.attachments,
                 ),
             )
@@ -220,7 +266,15 @@ class ComposeViewModel @Inject constructor(
                 else -> {
                     _state.update { it.copy(sending = true, error = null) }
                     mailRepository.sendMessage(
-                        OutgoingMessage(account.id, s.to, s.cc, s.subject, s.body, s.attachments),
+                        OutgoingMessage(
+                            accountId = account.id,
+                            to = s.to,
+                            cc = s.cc,
+                            subject = s.subject,
+                            body = s.body,
+                            bodyHtml = s.bodyHtml,
+                            attachments = s.attachments,
+                        ),
                     ).fold(
                         onSuccess = {
                             draftId?.let { mailRepository.deleteDraft(it) }
diff --git a/app/src/main/kotlin/org/libremail/ui/compose/RichTextEditor.kt b/app/src/main/kotlin/org/libremail/ui/compose/RichTextEditor.kt
new file mode 100644
index 0000000..95a51b2
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/ui/compose/RichTextEditor.kt
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.ui.compose
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.LocalTextStyle
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.Role
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.SpanStyle
+import androidx.compose.ui.text.TextRange
+import androidx.compose.ui.text.buildAnnotatedString
+import androidx.compose.ui.text.font.FontStyle
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.text.input.TextFieldValue
+import androidx.compose.ui.text.style.TextDecoration
+import androidx.compose.ui.unit.dp
+import org.libremail.R
+import org.libremail.richtext.BlockMarker
+import org.libremail.richtext.RichLink
+import org.libremail.richtext.RichSpan
+import org.libremail.richtext.RichStyle
+import org.libremail.richtext.RichTextContent
+import org.libremail.richtext.RichTextEditing
+import org.libremail.richtext.RichTextHtml
+
+/** String-annotation tag the editor uses to carry a span's link target inside the [AnnotatedString]. */
+private const val URL_TAG = "libremail:url"
+
+/**
+ * A rich-text body editor: a formatting toolbar (bold / italic / underline, bulleted + numbered
+ * lists, block quote, and link) above a rounded [OutlinedTextField]. It converts its
+ * [AnnotatedString] to the app's [RichTextContent] model and reports both the plaintext form and its
+ * HTML — or null HTML when nothing is formatted, so an unformatted message stays plaintext-only and
+ * feels exactly like the old editor.
+ *
+ * The field is a normal Compose text field, so TalkBack, text selection, and large system fonts all
+ * work as usual; the toolbar buttons carry content descriptions and toggle state for accessibility.
+ */
+@Composable
+fun RichTextBodyField(
+    body: String,
+    bodyHtml: String?,
+    onBodyChange: (plain: String, html: String?) -> Unit,
+    label: String,
+    modifier: Modifier = Modifier,
+) {
+    val linkColor = MaterialTheme.colorScheme.primary
+    var value by remember { mutableStateOf(seedValue(body, bodyHtml, linkColor)) }
+    // Tracks the (plain, html) we last pushed up, so an external change (draft load / signature swap)
+    // re-seeds the field but our own emissions do not fight the user's cursor.
+    var lastEmitted by remember { mutableStateOf(body to bodyHtml) }
+
+    if (body to bodyHtml != lastEmitted) {
+        value = seedValue(body, bodyHtml, linkColor)
+        lastEmitted = body to bodyHtml
+    }
+
+    fun emit(newValue: TextFieldValue) {
+        value = newValue
+        val content = newValue.annotatedString.toRichContent()
+        val html = if (content.hasFormatting()) RichTextHtml.toHtml(content) else null
+        lastEmitted = content.text to html
+        onBodyChange(content.text, html)
+    }
+
+    var showLinkDialog by remember { mutableStateOf(false) }
+
+    Column(modifier) {
+        FormattingToolbar(
+            value = value,
+            onToggleStyle = { style -> emit(applyStyle(value, style, linkColor)) },
+            onToggleBlock = { marker -> emit(applyBlock(value, marker, linkColor)) },
+            onLink = { showLinkDialog = true },
+        )
+        OutlinedTextField(
+            value = value,
+            onValueChange = ::emit,
+            label = { Text(label) },
+            shape = MaterialTheme.shapes.large,
+            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Text),
+            modifier = Modifier.fillMaxWidth().weight(1f),
+        )
+    }
+
+    if (showLinkDialog) {
+        val hasSelection = value.selection.min < value.selection.max
+        LinkDialog(
+            enabled = hasSelection,
+            onDismiss = { showLinkDialog = false },
+            onConfirm = { url ->
+                emit(applyLink(value, url, linkColor))
+                showLinkDialog = false
+            },
+        )
+    }
+}
+
+@Composable
+private fun FormattingToolbar(
+    value: TextFieldValue,
+    onToggleStyle: (RichStyle) -> Unit,
+    onToggleBlock: (BlockMarker) -> Unit,
+    onLink: () -> Unit,
+) {
+    val content = value.annotatedString.toRichContent()
+    val start = value.selection.min
+    val end = value.selection.max
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .horizontalScroll(rememberScrollState())
+            .padding(vertical = 4.dp),
+        horizontalArrangement = Arrangement.spacedBy(2.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        FormatButton(
+            label = "B",
+            description = stringResource(R.string.format_bold),
+            active = RichTextEditing.isStyled(content, start, end, RichStyle.BOLD),
+            fontWeight = FontWeight.Bold,
+            onClick = { onToggleStyle(RichStyle.BOLD) },
+        )
+        FormatButton(
+            label = "I",
+            description = stringResource(R.string.format_italic),
+            active = RichTextEditing.isStyled(content, start, end, RichStyle.ITALIC),
+            fontStyle = FontStyle.Italic,
+            onClick = { onToggleStyle(RichStyle.ITALIC) },
+        )
+        FormatButton(
+            label = "U",
+            description = stringResource(R.string.format_underline),
+            active = RichTextEditing.isStyled(content, start, end, RichStyle.UNDERLINE),
+            underline = true,
+            onClick = { onToggleStyle(RichStyle.UNDERLINE) },
+        )
+        FormatButton(
+            label = "•",
+            description = stringResource(R.string.format_bullet_list),
+            active = RichTextEditing.hasBlock(content, start, end, BlockMarker.BULLET),
+            onClick = { onToggleBlock(BlockMarker.BULLET) },
+        )
+        FormatButton(
+            label = "1.",
+            description = stringResource(R.string.format_numbered_list),
+            active = RichTextEditing.hasBlock(content, start, end, BlockMarker.ORDERED),
+            onClick = { onToggleBlock(BlockMarker.ORDERED) },
+        )
+        FormatButton(
+            label = "❝",
+            description = stringResource(R.string.format_quote),
+            active = RichTextEditing.hasBlock(content, start, end, BlockMarker.QUOTE),
+            onClick = { onToggleBlock(BlockMarker.QUOTE) },
+        )
+        FormatButton(
+            label = "🔗",
+            description = stringResource(R.string.format_link),
+            active = false,
+            onClick = onLink,
+        )
+    }
+}
+
+@Composable
+private fun FormatButton(
+    label: String,
+    description: String,
+    active: Boolean,
+    onClick: () -> Unit,
+    fontWeight: FontWeight? = null,
+    fontStyle: FontStyle? = null,
+    underline: Boolean = false,
+) {
+    val colors = MaterialTheme.colorScheme
+    val background = if (active) colors.secondaryContainer else Color.Transparent
+    val textColor = if (active) colors.onSecondaryContainer else colors.onSurfaceVariant
+    Box(
+        modifier = Modifier
+            .clip(MaterialTheme.shapes.small)
+            .background(background)
+            .clickable(onClick = onClick, role = Role.Button, onClickLabel = description)
+            .padding(horizontal = 12.dp, vertical = 8.dp),
+        contentAlignment = Alignment.Center,
+    ) {
+        Text(
+            text = label,
+            color = textColor,
+            style = LocalTextStyle.current.copy(
+                fontWeight = fontWeight,
+                fontStyle = fontStyle,
+                textDecoration = if (underline) TextDecoration.Underline else null,
+            ),
+        )
+    }
+}
+
+@Composable
+private fun LinkDialog(enabled: Boolean, onDismiss: () -> Unit, onConfirm: (String) -> Unit) {
+    var url by remember { mutableStateOf("") }
+    AlertDialog(
+        onDismissRequest = onDismiss,
+        title = { Text(stringResource(R.string.format_link_title)) },
+        text = {
+            if (enabled) {
+                OutlinedTextField(
+                    value = url,
+                    onValueChange = { url = it },
+                    singleLine = true,
+                    label = { Text(stringResource(R.string.format_link_url)) },
+                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Uri),
+                    modifier = Modifier.fillMaxWidth(),
+                )
+            } else {
+                Text(stringResource(R.string.format_link_needs_selection))
+            }
+        },
+        confirmButton = {
+            TextButton(onClick = { onConfirm(url.trim()) }, enabled = enabled && url.isNotBlank()) {
+                Text(stringResource(R.string.format_link_apply))
+            }
+        },
+        dismissButton = { TextButton(onClick = onDismiss) { Text(stringResource(R.string.cancel)) } },
+    )
+}
+
+// --- editor-op plumbing (TextFieldValue <-> RichTextContent) ---
+
+private fun applyStyle(value: TextFieldValue, style: RichStyle, linkColor: Color): TextFieldValue {
+    val updated = RichTextEditing.toggleStyle(
+        value.annotatedString.toRichContent(),
+        value.selection.min,
+        value.selection.max,
+        style,
+    )
+    return TextFieldValue(updated.toAnnotatedString(linkColor), value.selection)
+}
+
+private fun applyBlock(value: TextFieldValue, marker: BlockMarker, linkColor: Color): TextFieldValue {
+    val result = RichTextEditing.toggleBlock(
+        value.annotatedString.toRichContent(),
+        value.selection.min,
+        value.selection.max,
+        marker,
+    )
+    return TextFieldValue(
+        result.content.toAnnotatedString(linkColor),
+        TextRange(result.selectionStart, result.selectionEnd),
+    )
+}
+
+private fun applyLink(value: TextFieldValue, url: String, linkColor: Color): TextFieldValue {
+    val updated = RichTextEditing.applyLink(
+        value.annotatedString.toRichContent(),
+        value.selection.min,
+        value.selection.max,
+        url,
+    )
+    return TextFieldValue(updated.toAnnotatedString(linkColor), value.selection)
+}
+
+private fun seedValue(body: String, bodyHtml: String?, linkColor: Color): TextFieldValue {
+    val content = if (bodyHtml != null) RichTextHtml.fromHtml(bodyHtml) else RichTextContent(body)
+    val annotated = content.toAnnotatedString(linkColor)
+    return TextFieldValue(annotated, TextRange(annotated.length))
+}
+
+/** Maps the app rich-text model onto a Compose [AnnotatedString] for display/editing. */
+internal fun RichTextContent.toAnnotatedString(linkColor: Color): AnnotatedString = buildAnnotatedString {
+    append(text)
+    spans.forEach { span -> addStyle(spanStyleFor(span.style), span.start, span.end) }
+    links.forEach { link ->
+        addStyle(SpanStyle(color = linkColor), link.start, link.end)
+        addStringAnnotation(URL_TAG, link.url, link.start, link.end)
+    }
+}
+
+/** Maps a Compose [AnnotatedString] back to the app model, reading single-attribute span styles. */
+internal fun AnnotatedString.toRichContent(): RichTextContent {
+    val richSpans = spanStyles.mapNotNull { range ->
+        styleOf(range.item)?.let { RichSpan(range.start, range.end, it) }
+    }
+    val links = getStringAnnotations(URL_TAG, 0, length).map { RichLink(it.start, it.end, it.item) }
+    return RichTextContent(text, richSpans, links)
+}
+
+private fun spanStyleFor(style: RichStyle): SpanStyle = when (style) {
+    RichStyle.BOLD -> SpanStyle(fontWeight = FontWeight.Bold)
+    RichStyle.ITALIC -> SpanStyle(fontStyle = FontStyle.Italic)
+    RichStyle.UNDERLINE -> SpanStyle(textDecoration = TextDecoration.Underline)
+}
+
+private fun styleOf(span: SpanStyle): RichStyle? = when {
+    span.fontWeight == FontWeight.Bold -> RichStyle.BOLD
+    span.fontStyle == FontStyle.Italic -> RichStyle.ITALIC
+    span.textDecoration == TextDecoration.Underline -> RichStyle.UNDERLINE
+    else -> null // e.g. the link color span, which is carried by the URL annotation instead
+}
diff --git a/app/src/main/kotlin/org/libremail/ui/navigation/Routes.kt b/app/src/main/kotlin/org/libremail/ui/navigation/Routes.kt
index 5ddb2d5..76ae954 100644
--- a/app/src/main/kotlin/org/libremail/ui/navigation/Routes.kt
+++ b/app/src/main/kotlin/org/libremail/ui/navigation/Routes.kt
@@ -20,6 +20,17 @@ object Routes {
     const val ACCOUNT_SETTINGS_PATTERN = "account_settings/{$ACCOUNT_SETTINGS_ARG_ID}"
     fun accountSettings(accountId: String) = "account_settings/${Uri.encode(accountId)}"
 
+    const val SIGNATURES_ARG_ACCOUNT = "accountId"
+    const val SIGNATURES_PATTERN = "signatures/{$SIGNATURES_ARG_ACCOUNT}"
+    fun signatures(accountId: String) = "signatures/${Uri.encode(accountId)}"
+
+    const val SIGNATURE_EDIT_ARG_ACCOUNT = "accountId"
+    const val SIGNATURE_EDIT_ARG_ID = "signatureId"
+    const val SIGNATURE_EDIT_PATTERN =
+        "signature_edit/{$SIGNATURE_EDIT_ARG_ACCOUNT}?$SIGNATURE_EDIT_ARG_ID={$SIGNATURE_EDIT_ARG_ID}"
+    fun signatureEdit(accountId: String, signatureId: String = ""): String =
+        "signature_edit/${Uri.encode(accountId)}?$SIGNATURE_EDIT_ARG_ID=${Uri.encode(signatureId)}"
+
     const val COMPOSE_ARG_TO = "to"
     const val COMPOSE_ARG_SUBJECT = "subject"
     const val COMPOSE_ARG_FROM = "from"
diff --git a/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsScreen.kt b/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsScreen.kt
index 07e1c38..bdb68b5 100644
--- a/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsScreen.kt
+++ b/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsScreen.kt
@@ -6,7 +6,6 @@ import android.content.Intent
 import android.provider.Settings
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
@@ -17,7 +16,6 @@ import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Text
 import androidx.compose.material3.TopAppBar
@@ -26,17 +24,21 @@ import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import org.libremail.R
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun AccountSettingsScreen(onBack: () -> Unit, viewModel: AccountSettingsViewModel = hiltViewModel()) {
+fun AccountSettingsScreen(
+    onBack: () -> Unit,
+    onManageSignatures: () -> Unit,
+    viewModel: AccountSettingsViewModel = hiltViewModel(),
+) {
     val account by viewModel.account.collectAsStateWithLifecycle()
     val settings by viewModel.settings.collectAsStateWithLifecycle()
-    val signature by viewModel.signature.collectAsStateWithLifecycle()
+    val signatureCount by viewModel.signatureCount.collectAsStateWithLifecycle()
+    val defaultSignatureName by viewModel.defaultSignatureName.collectAsStateWithLifecycle()
     val context = LocalContext.current
     val fallbackTitle = stringResource(R.string.settings_account_title)
 
@@ -67,15 +69,14 @@ fun AccountSettingsScreen(onBack: () -> Unit, viewModel: AccountSettingsViewMode
                 checked = settings.signatureEnabled,
                 onCheckedChange = viewModel::setSignatureEnabled,
             )
-            OutlinedTextField(
-                value = signature ?: "",
-                onValueChange = viewModel::onSignatureChange,
-                enabled = settings.signatureEnabled,
-                label = { Text(stringResource(R.string.settings_signature_hint)) },
-                minLines = 3,
-                modifier = Modifier
-                    .fillMaxWidth()
-                    .padding(horizontal = 16.dp, vertical = 8.dp),
+            ClickRow(
+                title = stringResource(R.string.settings_signatures_manage),
+                subtitle = if (signatureCount == 0) {
+                    stringResource(R.string.settings_signatures_summary_none)
+                } else {
+                    stringResource(R.string.settings_signatures_summary, signatureCount, defaultSignatureName)
+                },
+                onClick = onManageSignatures,
             )
             HorizontalDivider()
 
diff --git a/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsViewModel.kt b/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsViewModel.kt
index 2436360..733cd74 100644
--- a/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsViewModel.kt
+++ b/app/src/main/kotlin/org/libremail/ui/settings/AccountSettingsViewModel.kt
@@ -5,15 +5,13 @@ import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
-import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
-import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import org.libremail.data.settings.AccountSettingsRepository
+import org.libremail.data.settings.SignatureRepository
 import org.libremail.domain.model.Account
 import org.libremail.domain.model.AccountSettings
 import org.libremail.domain.repository.AccountRepository
@@ -26,6 +24,7 @@ class AccountSettingsViewModel @Inject constructor(
     savedStateHandle: SavedStateHandle,
     private val accountRepository: AccountRepository,
     private val accountSettingsRepository: AccountSettingsRepository,
+    signatureRepository: SignatureRepository,
 ) : ViewModel() {
 
     private val accountId: String =
@@ -38,26 +37,20 @@ class AccountSettingsViewModel @Inject constructor(
     val settings: StateFlow<AccountSettings> = accountSettingsRepository.observe(accountId)
         .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), AccountSettings(accountId))
 
-    // The signature text is edited locally (seeded once from persistence) so the field stays
-    // responsive — a fully DB-driven value would lag each keystroke and jump the cursor.
-    private val _signature = MutableStateFlow<String?>(null)
-    val signature: StateFlow<String?> = _signature.asStateFlow()
+    private val signaturesFlow = signatureRepository.observeForAccount(accountId)
+
+    val signatureCount: StateFlow<Int> = signaturesFlow
+        .map { it.size }
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), 0)
+
+    /** The name of the account's default signature (for the settings summary line), or "". */
+    val defaultSignatureName: StateFlow<String> = signaturesFlow
+        .map { list -> list.firstOrNull { it.isDefault }?.name ?: list.firstOrNull()?.name ?: "" }
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), "")
 
     /** This account's notification channel id, for deep-linking into Android's system settings. */
     val notificationChannelId: String = MailNotifier.channelId(accountId)
 
-    init {
-        viewModelScope.launch {
-            val loaded = accountSettingsRepository.get(accountId).signature
-            _signature.update { it ?: loaded } // don't clobber any text typed before the load returned
-        }
-    }
-
-    fun onSignatureChange(value: String) {
-        _signature.value = value
-        viewModelScope.launch { accountSettingsRepository.setSignature(accountId, value) }
-    }
-
     fun setSignatureEnabled(value: Boolean) {
         viewModelScope.launch { accountSettingsRepository.setSignatureEnabled(accountId, value) }
     }
diff --git a/app/src/main/kotlin/org/libremail/ui/settings/SignatureEditScreen.kt b/app/src/main/kotlin/org/libremail/ui/settings/SignatureEditScreen.kt
new file mode 100644
index 0000000..b656ebd
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/ui/settings/SignatureEditScreen.kt
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.ui.settings
+
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import org.libremail.R
+import org.libremail.ui.compose.RichTextBodyField
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun SignatureEditScreen(onBack: () -> Unit, viewModel: SignatureEditViewModel = hiltViewModel()) {
+    val state by viewModel.state.collectAsStateWithLifecycle()
+
+    Scaffold(
+        topBar = {
+            TopAppBar(
+                title = {
+                    Text(
+                        stringResource(
+                            if (viewModel.isNew) R.string.signature_new_title else R.string.signature_edit_title,
+                        ),
+                    )
+                },
+                navigationIcon = {
+                    IconButton(onClick = onBack) {
+                        Icon(
+                            Icons.AutoMirrored.Filled.ArrowBack,
+                            contentDescription = stringResource(R.string.action_back),
+                        )
+                    }
+                },
+                actions = {
+                    TextButton(onClick = { viewModel.save(onBack) }) {
+                        Text(stringResource(R.string.signature_save))
+                    }
+                },
+            )
+        },
+    ) { padding ->
+        Column(
+            Modifier
+                .fillMaxSize()
+                .padding(padding)
+                .padding(16.dp),
+        ) {
+            OutlinedTextField(
+                value = state.name,
+                onValueChange = viewModel::onNameChange,
+                label = { Text(stringResource(R.string.signature_name)) },
+                singleLine = true,
+                shape = MaterialTheme.shapes.medium,
+                modifier = Modifier.fillMaxWidth(),
+            )
+            Spacer(Modifier.height(8.dp))
+            // Reuse the compose editor so signatures are rich in exactly the same way message bodies are.
+            if (state.loaded) {
+                RichTextBodyField(
+                    body = state.body,
+                    bodyHtml = state.bodyHtml,
+                    onBodyChange = viewModel::onBodyChange,
+                    label = stringResource(R.string.signature_content),
+                    modifier = Modifier.fillMaxWidth().weight(1f),
+                )
+            }
+        }
+    }
+}
diff --git a/app/src/main/kotlin/org/libremail/ui/settings/SignatureEditViewModel.kt b/app/src/main/kotlin/org/libremail/ui/settings/SignatureEditViewModel.kt
new file mode 100644
index 0000000..3bfe833
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/ui/settings/SignatureEditViewModel.kt
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.ui.settings
+
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+import org.libremail.data.settings.SignatureRepository
+import org.libremail.richtext.RichTextContent
+import org.libremail.richtext.RichTextHtml
+import org.libremail.ui.navigation.Routes
+import javax.inject.Inject
+
+data class SignatureEditUiState(
+    val name: String = "",
+    val body: String = "",
+    val bodyHtml: String? = null,
+    val loaded: Boolean = false,
+)
+
+@HiltViewModel
+class SignatureEditViewModel @Inject constructor(
+    savedStateHandle: SavedStateHandle,
+    private val signatureRepository: SignatureRepository,
+) : ViewModel() {
+
+    private val accountId: String = checkNotNull(savedStateHandle[Routes.SIGNATURE_EDIT_ARG_ACCOUNT])
+    private val signatureId: String? =
+        savedStateHandle.get<String>(Routes.SIGNATURE_EDIT_ARG_ID)?.takeIf { it.isNotBlank() }
+
+    val isNew: Boolean = signatureId == null
+
+    private val _state = MutableStateFlow(SignatureEditUiState(loaded = isNew))
+    val state: StateFlow<SignatureEditUiState> = _state.asStateFlow()
+
+    init {
+        if (signatureId != null) {
+            viewModelScope.launch {
+                signatureRepository.get(signatureId)?.let { signature ->
+                    _state.update {
+                        it.copy(
+                            name = signature.name,
+                            body = signature.plainText(),
+                            bodyHtml = signature.html.ifBlank { null },
+                            loaded = true,
+                        )
+                    }
+                }
+            }
+        }
+    }
+
+    fun onNameChange(value: String) = _state.update { it.copy(name = value) }
+
+    fun onBodyChange(plain: String, html: String?) = _state.update { it.copy(body = plain, bodyHtml = html) }
+
+    /** Persists the signature (create or update), then invokes [onSaved]. */
+    fun save(onSaved: () -> Unit) {
+        val s = _state.value
+        val name = s.name.trim().ifBlank { DEFAULT_NAME }
+        // Store real HTML so the signature round-trips; derive it from the plaintext when unformatted.
+        val html = s.bodyHtml ?: RichTextHtml.toHtml(RichTextContent(s.body))
+        viewModelScope.launch {
+            if (signatureId == null) {
+                signatureRepository.create(accountId, name, html)
+            } else {
+                signatureRepository.update(signatureId, name, html)
+            }
+            onSaved()
+        }
+    }
+
+    private companion object {
+        const val DEFAULT_NAME = "Signature"
+    }
+}
diff --git a/app/src/main/kotlin/org/libremail/ui/settings/SignaturesScreen.kt b/app/src/main/kotlin/org/libremail/ui/settings/SignaturesScreen.kt
new file mode 100644
index 0000000..25ef189
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/ui/settings/SignaturesScreen.kt
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.ui.settings
+
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.filled.Add
+import androidx.compose.material.icons.filled.Delete
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FloatingActionButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.RadioButton
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import org.libremail.R
+import org.libremail.domain.model.Signature
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun SignaturesScreen(
+    onBack: () -> Unit,
+    onEdit: (signatureId: String) -> Unit,
+    onAdd: () -> Unit,
+    viewModel: SignaturesViewModel = hiltViewModel(),
+) {
+    val signatures by viewModel.signatures.collectAsStateWithLifecycle()
+
+    Scaffold(
+        topBar = {
+            TopAppBar(
+                title = { Text(stringResource(R.string.signatures_title)) },
+                navigationIcon = {
+                    IconButton(onClick = onBack) {
+                        Icon(
+                            Icons.AutoMirrored.Filled.ArrowBack,
+                            contentDescription = stringResource(R.string.action_back),
+                        )
+                    }
+                },
+            )
+        },
+        floatingActionButton = {
+            FloatingActionButton(onClick = onAdd) {
+                Icon(Icons.Filled.Add, contentDescription = stringResource(R.string.signatures_add))
+            }
+        },
+    ) { padding ->
+        if (signatures.isEmpty()) {
+            Box(Modifier.fillMaxSize().padding(padding).padding(32.dp), contentAlignment = Alignment.Center) {
+                Text(
+                    stringResource(R.string.signatures_empty),
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            }
+        } else {
+            LazyColumn(Modifier.fillMaxSize().padding(padding)) {
+                items(signatures, key = { it.id }) { signature ->
+                    SignatureRow(
+                        signature = signature,
+                        onClick = { onEdit(signature.id) },
+                        onMakeDefault = { viewModel.setDefault(signature.id) },
+                        onDelete = { viewModel.delete(signature.id) },
+                    )
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun SignatureRow(signature: Signature, onClick: () -> Unit, onMakeDefault: () -> Unit, onDelete: () -> Unit) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .clickable(onClick = onClick)
+            .padding(horizontal = 8.dp, vertical = 4.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(4.dp),
+    ) {
+        RadioButton(
+            selected = signature.isDefault,
+            onClick = onMakeDefault,
+        )
+        Column(Modifier.weight(1f)) {
+            Text(
+                signature.name.ifBlank { stringResource(R.string.signature_content) },
+                style = MaterialTheme.typography.bodyLarge,
+                maxLines = 1,
+                overflow = TextOverflow.Ellipsis,
+            )
+            val preview = signature.plainText().replace('\n', ' ').trim()
+            if (preview.isNotEmpty()) {
+                Text(
+                    preview,
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+            }
+            if (signature.isDefault) {
+                Text(
+                    stringResource(R.string.signature_default_badge),
+                    style = MaterialTheme.typography.labelSmall,
+                    color = MaterialTheme.colorScheme.primary,
+                )
+            }
+        }
+        IconButton(onClick = onDelete) {
+            Icon(Icons.Filled.Delete, contentDescription = stringResource(R.string.signature_delete))
+        }
+    }
+}
diff --git a/app/src/main/kotlin/org/libremail/ui/settings/SignaturesViewModel.kt b/app/src/main/kotlin/org/libremail/ui/settings/SignaturesViewModel.kt
new file mode 100644
index 0000000..baa6b94
--- /dev/null
+++ b/app/src/main/kotlin/org/libremail/ui/settings/SignaturesViewModel.kt
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.ui.settings
+
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
+import org.libremail.data.settings.SignatureRepository
+import org.libremail.domain.model.Signature
+import org.libremail.ui.navigation.Routes
+import javax.inject.Inject
+
+@HiltViewModel
+class SignaturesViewModel @Inject constructor(
+    savedStateHandle: SavedStateHandle,
+    private val signatureRepository: SignatureRepository,
+) : ViewModel() {
+
+    val accountId: String = checkNotNull(savedStateHandle[Routes.SIGNATURES_ARG_ACCOUNT])
+
+    val signatures: StateFlow<List<Signature>> = signatureRepository.observeForAccount(accountId)
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyList())
+
+    fun setDefault(id: String) {
+        viewModelScope.launch { signatureRepository.setDefault(accountId, id) }
+    }
+
+    fun delete(id: String) {
+        viewModelScope.launch { signatureRepository.delete(id) }
+    }
+}
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index a4df47f..5f5363b 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -77,6 +77,19 @@
     <string name="compose_attach">Attach file</string>
     <string name="compose_attachment_remove">Remove attachment</string>
 
+    <!-- Compose formatting toolbar -->
+    <string name="format_bold">Bold</string>
+    <string name="format_italic">Italic</string>
+    <string name="format_underline">Underline</string>
+    <string name="format_bullet_list">Bulleted list</string>
+    <string name="format_numbered_list">Numbered list</string>
+    <string name="format_quote">Block quote</string>
+    <string name="format_link">Insert link</string>
+    <string name="format_link_title">Insert link</string>
+    <string name="format_link_url">Link address</string>
+    <string name="format_link_apply">Link</string>
+    <string name="format_link_needs_selection">Select some text first, then add a link.</string>
+
     <!-- Drafts -->
     <string name="drafts_title">Drafts</string>
     <string name="drafts_empty">No drafts</string>
@@ -146,8 +159,25 @@
     <!-- Per-account settings -->
     <string name="settings_account_title">Account</string>
     <string name="settings_signature">Signature</string>
-    <string name="settings_signature_enable">Append signature</string>
+    <string name="settings_signature_enable">Append signature automatically</string>
     <string name="settings_signature_hint">Your signature</string>
+    <string name="settings_signatures_manage">Manage signatures</string>
+    <string name="settings_signatures_summary_none">No signatures yet</string>
+    <string name="settings_signatures_summary">%1$d signature(s), default: %2$s</string>
+
+    <!-- Signatures management -->
+    <string name="signatures_title">Signatures</string>
+    <string name="signatures_empty">No signatures yet. Add one to append it to your messages.</string>
+    <string name="signatures_add">Add signature</string>
+    <string name="signature_new_title">New signature</string>
+    <string name="signature_edit_title">Edit signature</string>
+    <string name="signature_name">Name</string>
+    <string name="signature_content">Signature</string>
+    <string name="signature_save">Save</string>
+    <string name="signature_delete">Delete signature</string>
+    <string name="signature_default">Default</string>
+    <string name="signature_make_default">Set as default</string>
+    <string name="signature_default_badge">Default</string>
     <string name="settings_account_notifications">Notifications</string>
     <string name="settings_account_new_mail">New mail notifications</string>
     <string name="settings_account_new_mail_summary">Show notifications for this account</string>
diff --git a/app/src/test/kotlin/org/libremail/data/ReplyBuilderTest.kt b/app/src/test/kotlin/org/libremail/data/ReplyBuilderTest.kt
index 5475d28..49fc6c2 100644
--- a/app/src/test/kotlin/org/libremail/data/ReplyBuilderTest.kt
+++ b/app/src/test/kotlin/org/libremail/data/ReplyBuilderTest.kt
@@ -105,4 +105,26 @@ class ReplyBuilderTest {
         assertTrue(result.body.contains("Hello"), "body=${result.body}")
         assertTrue(result.body.contains("there"), "body=${result.body}")
     }
+
+    @Test
+    fun `html original is quoted into a blockquote without leaking original tags`() {
+        val result = ReplyBuilder.build(
+            context(body = "<p>Hello <b>there</b></p>", isHtml = true),
+            ReplyMode.REPLY,
+            "me@example.org",
+        )
+
+        // The HTML alternative wraps the (tag-stripped) original in a blockquote — never raw tags.
+        assertTrue(result.bodyHtml.contains("<blockquote>"), "html=${result.bodyHtml}")
+        assertTrue(result.bodyHtml.contains("Hello there"), "html=${result.bodyHtml}")
+        assertFalse(result.bodyHtml.contains("<p>Hello"), "html=${result.bodyHtml}")
+    }
+
+    @Test
+    fun `plaintext reply also carries an html blockquote alternative`() {
+        val result = ReplyBuilder.build(context(body = "First line\nSecond line"), ReplyMode.REPLY, "me@example.org")
+
+        assertTrue(result.bodyHtml.contains("<blockquote>"), "html=${result.bodyHtml}")
+        assertTrue(result.bodyHtml.contains("First line"), "html=${result.bodyHtml}")
+    }
 }
diff --git a/app/src/test/kotlin/org/libremail/data/SignatureBlockTest.kt b/app/src/test/kotlin/org/libremail/data/SignatureBlockTest.kt
new file mode 100644
index 0000000..b3c7119
--- /dev/null
+++ b/app/src/test/kotlin/org/libremail/data/SignatureBlockTest.kt
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.data
+
+import org.junit.Test
+import org.libremail.domain.model.Signature
+import org.libremail.richtext.RichTextHtml
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class SignatureBlockTest {
+
+    private fun signature(html: String) =
+        Signature(id = "s", accountId = "a", name = "Sig", html = html, isDefault = true)
+
+    @Test
+    fun `plain form opens with the RFC 3676 delimiter`() {
+        val block = SignatureBlock.of(signature("Cheers, Alice"))
+        assertEquals("\n\n-- \nCheers, Alice", block.plain)
+    }
+
+    @Test
+    fun `html form parses back to exactly the plain form`() {
+        val block = SignatureBlock.of(signature("Cheers, Alice"))
+        assertEquals(block.plain, RichTextHtml.fromHtml(block.html).text)
+    }
+
+    @Test
+    fun `a rich signature keeps its formatting in the html form`() {
+        val block = SignatureBlock.of(signature("Cheers, <b>Alice</b>"))
+        assertTrue(block.html.endsWith("Cheers, <b>Alice</b>"), block.html)
+        assertEquals("\n\n-- \nCheers, Alice", block.plain)
+    }
+
+    @Test
+    fun `null or blank signature yields the empty block`() {
+        assertTrue(SignatureBlock.of(null).isEmpty)
+        assertTrue(SignatureBlock.of(signature("")).isEmpty)
+    }
+}
diff --git a/app/src/test/kotlin/org/libremail/data/local/MappersHtmlBodyTest.kt b/app/src/test/kotlin/org/libremail/data/local/MappersHtmlBodyTest.kt
new file mode 100644
index 0000000..2e57478
--- /dev/null
+++ b/app/src/test/kotlin/org/libremail/data/local/MappersHtmlBodyTest.kt
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.data.local
+
+import org.junit.Test
+import org.libremail.data.local.entity.OutboxEntity
+import org.libremail.domain.model.Draft
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class MappersHtmlBodyTest {
+
+    @Test
+    fun `draft html body round-trips through the entity`() {
+        val draft = Draft(
+            id = "d1",
+            accountId = "acct",
+            to = "a@x.com",
+            cc = "",
+            subject = "Hi",
+            body = "Hello",
+            updatedAt = 1L,
+            bodyHtml = "<p>Hello <b>there</b></p>",
+        )
+
+        val restored = draft.toEntity().toDomain()
+
+        assertEquals("<p>Hello <b>there</b></p>", restored.bodyHtml)
+        assertEquals("Hello", restored.body)
+    }
+
+    @Test
+    fun `a plaintext draft keeps a null html body`() {
+        val draft = Draft("d2", "acct", "a@x.com", "", "Hi", "Hello", 1L)
+        assertNull(draft.toEntity().toDomain().bodyHtml)
+    }
+
+    @Test
+    fun `outbox entity maps its html body to the domain`() {
+        val entity = OutboxEntity(
+            id = "o1",
+            accountId = "acct",
+            toAddresses = "a@x.com",
+            ccAddresses = "",
+            subject = "Hi",
+            body = "Hello",
+            createdAt = 1L,
+            bodyHtml = "<p>Hi</p>",
+        )
+
+        assertEquals("<p>Hi</p>", entity.toDomain().bodyHtml)
+    }
+}
diff --git a/app/src/test/kotlin/org/libremail/data/repository/MailRepositoryImplTest.kt b/app/src/test/kotlin/org/libremail/data/repository/MailRepositoryImplTest.kt
index 56edec2..a40ed20 100644
--- a/app/src/test/kotlin/org/libremail/data/repository/MailRepositoryImplTest.kt
+++ b/app/src/test/kotlin/org/libremail/data/repository/MailRepositoryImplTest.kt
@@ -25,6 +25,7 @@ import org.libremail.data.local.entity.FolderEntity
 import org.libremail.data.local.entity.MessageEntity
 import org.libremail.data.local.entity.ServerConfigEmbedded
 import org.libremail.data.settings.AccountSettingsRepository
+import org.libremail.data.settings.SignatureRepository
 import org.libremail.data.sync.MailConnectionFactory
 import org.libremail.domain.model.AccountSettings
 import org.libremail.domain.model.FolderRole
@@ -54,6 +55,7 @@ class MailRepositoryImplTest {
     private val connectionFactory = mockk<MailConnectionFactory>()
     private val context = mockk<Context>(relaxed = true)
     private val accountSettingsRepository = mockk<AccountSettingsRepository>()
+    private val signatureRepository = mockk<SignatureRepository>()
     private val repository = MailRepositoryImpl(
         context = context,
         messageDao = messageDao,
@@ -66,6 +68,7 @@ class MailRepositoryImplTest {
         connectionFactory = connectionFactory,
         sendScheduler = mockk(),
         accountSettingsRepository = accountSettingsRepository,
+        signatureRepository = signatureRepository,
     )
 
     @Test
@@ -202,6 +205,7 @@ class MailRepositoryImplTest {
         coEvery { messageDao.getById(id) } returns messageEntity(id, "INBOX")
         coEvery { accountDao.getById("acct") } returns accountEntity()
         coEvery { accountSettingsRepository.get(any()) } returns AccountSettings("acct")
+        coEvery { signatureRepository.getDefault(any()) } returns null
         coEvery { connectionFactory.imapParamsFor(any()) } returns imapParams()
         coEvery { imapClient.fetchForReply(any(), "INBOX", "2") } returns ReplyContext(
             fromEmail = "boss@example.org",
@@ -220,6 +224,42 @@ class MailRepositoryImplTest {
         assertTrue(result.isSuccess)
         assertEquals("boss@example.org", draft.captured.toAddresses)
         assertEquals("Re: Plan", draft.captured.subject)
+        // The reply carries an HTML alternative with the quote rendered as a blockquote.
+        assertTrue(draft.captured.bodyHtml?.contains("<blockquote>") == true, "html=${draft.captured.bodyHtml}")
+    }
+
+    @Test
+    fun `buildReplyDraft bakes the account default signature above the quote`() = runTest {
+        val id = "acct:INBOX:3"
+        coEvery { messageDao.getById(id) } returns messageEntity(id, "INBOX")
+        coEvery { accountDao.getById("acct") } returns accountEntity()
+        coEvery { accountSettingsRepository.get(any()) } returns AccountSettings("acct")
+        coEvery { signatureRepository.getDefault("acct") } returns org.libremail.domain.model.Signature(
+            id = "acct:sig",
+            accountId = "acct",
+            name = "Signature",
+            html = "Regards, Ada",
+            isDefault = true,
+        )
+        coEvery { connectionFactory.imapParamsFor(any()) } returns imapParams()
+        coEvery { imapClient.fetchForReply(any(), "INBOX", "3") } returns ReplyContext(
+            fromEmail = "boss@example.org",
+            toRecipients = listOf("ada@example.org"),
+            ccRecipients = emptyList(),
+            subject = "Plan",
+            sentDateMillis = 0L,
+            body = "Original",
+            isHtml = false,
+        )
+        val draft = slot<DraftEntity>()
+        coEvery { draftDao.upsert(capture(draft)) } just Runs
+
+        repository.buildReplyDraft(id, ReplyMode.REPLY)
+
+        val body = draft.captured.body
+        // Signature is placed before (above) the quoted original.
+        assertTrue(body.contains("Regards, Ada"), "body=$body")
+        assertTrue(body.indexOf("Regards, Ada") < body.indexOf("> Original"), "body=$body")
     }
 
     @Test
diff --git a/app/src/test/kotlin/org/libremail/data/settings/SignatureRepositoryTest.kt b/app/src/test/kotlin/org/libremail/data/settings/SignatureRepositoryTest.kt
new file mode 100644
index 0000000..b38c0df
--- /dev/null
+++ b/app/src/test/kotlin/org/libremail/data/settings/SignatureRepositoryTest.kt
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.data.settings
+
+import io.mockk.Runs
+import io.mockk.coEvery
+import io.mockk.coVerify
+import io.mockk.just
+import io.mockk.mockk
+import io.mockk.slot
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+import org.libremail.data.local.dao.SignatureDao
+import org.libremail.data.local.entity.SignatureEntity
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class SignatureRepositoryTest {
+
+    private val dao = mockk<SignatureDao>(relaxed = true)
+    private val repository = SignatureRepository(dao)
+
+    private fun entity(id: String, isDefault: Boolean) =
+        SignatureEntity(id, accountId = "acct", name = "N", contentHtml = "<p>x</p>", isDefault = isDefault)
+
+    @Test
+    fun `the first signature for an account becomes its default`() = runTest {
+        coEvery { dao.countForAccount("acct") } returns 0
+        val saved = slot<SignatureEntity>()
+        coEvery { dao.upsert(capture(saved)) } just Runs
+
+        repository.create("acct", "Work", "<p>hi</p>")
+
+        assertTrue(saved.captured.isDefault)
+    }
+
+    @Test
+    fun `later signatures are not made default`() = runTest {
+        coEvery { dao.countForAccount("acct") } returns 2
+        val saved = slot<SignatureEntity>()
+        coEvery { dao.upsert(capture(saved)) } just Runs
+
+        repository.create("acct", "Personal", "<p>hey</p>")
+
+        assertFalse(saved.captured.isDefault)
+    }
+
+    @Test
+    fun `deleting the default promotes the first remaining signature`() = runTest {
+        coEvery { dao.getById("s1") } returns entity("s1", isDefault = true)
+        coEvery { dao.firstForAccount("acct") } returns entity("s2", isDefault = false)
+
+        repository.delete("s1")
+
+        coVerify { dao.delete("s1") }
+        coVerify { dao.markDefault("s2") }
+    }
+
+    @Test
+    fun `deleting a non-default signature promotes nothing`() = runTest {
+        coEvery { dao.getById("s2") } returns entity("s2", isDefault = false)
+
+        repository.delete("s2")
+
+        coVerify { dao.delete("s2") }
+        coVerify(exactly = 0) { dao.firstForAccount(any()) }
+        coVerify(exactly = 0) { dao.markDefault(any()) }
+    }
+
+    @Test
+    fun `setDefault delegates to the dao's atomic swap`() = runTest {
+        repository.setDefault("acct", "s1")
+        coVerify { dao.setDefault("acct", "s1") }
+    }
+}
diff --git a/app/src/test/kotlin/org/libremail/mail/GraphSenderTest.kt b/app/src/test/kotlin/org/libremail/mail/GraphSenderTest.kt
index 758f3af..0e9a25f 100644
--- a/app/src/test/kotlin/org/libremail/mail/GraphSenderTest.kt
+++ b/app/src/test/kotlin/org/libremail/mail/GraphSenderTest.kt
@@ -34,6 +34,28 @@ class GraphSenderTest {
         assertEquals("c@z.com", cc.getJSONObject(0).getJSONObject("emailAddress").getString("address"))
     }
 
+    @Test
+    fun `payload uses the HTML content type when a formatted body is present`() {
+        val message = OutgoingMessage(
+            accountId = "outlook:me@example.com",
+            to = "a@x.com",
+            subject = "Hi",
+            body = "Hello world",
+            bodyHtml = "<p>Hello <b>world</b></p>",
+        )
+        val body = JSONObject(buildSendMailPayload(message, emptyList()))
+            .getJSONObject("message").getJSONObject("body")
+        assertEquals("HTML", body.getString("contentType"))
+        assertEquals("<p>Hello <b>world</b></p>", body.getString("content"))
+    }
+
+    @Test
+    fun `payload falls back to plain text when there is no HTML body`() {
+        val body = JSONObject(buildSendMailPayload(message(to = "a@x.com"), emptyList()))
+            .getJSONObject("message").getJSONObject("body")
+        assertEquals("Text", body.getString("contentType"))
+    }
+
     @Test
     fun `recipients parse RFC822 display names into bare addresses`() {
         val json = JSONObject(
diff --git a/app/src/test/kotlin/org/libremail/mail/HtmlToTextTest.kt b/app/src/test/kotlin/org/libremail/mail/HtmlToTextTest.kt
new file mode 100644
index 0000000..a5e67be
--- /dev/null
+++ b/app/src/test/kotlin/org/libremail/mail/HtmlToTextTest.kt
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.mail
+
+import org.junit.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class HtmlToTextTest {
+
+    @Test
+    fun `strips inline tags and keeps the words`() {
+        assertEquals("Hello world", HtmlToText.convert("<p>Hello <b>world</b></p>"))
+    }
+
+    @Test
+    fun `br and paragraphs become line breaks`() {
+        assertEquals("Line one\nLine two", HtmlToText.convert("Line one<br>Line two"))
+        assertEquals("A\n\nB", HtmlToText.convert("<p>A</p><p>B</p>"))
+    }
+
+    @Test
+    fun `list items gain bullet markers`() {
+        assertEquals("• One\n• Two", HtmlToText.convert("<ul><li>One</li><li>Two</li></ul>"))
+    }
+
+    @Test
+    fun `decodes entities and drops script and style content`() {
+        assertEquals("Tom & Jerry", HtmlToText.convert("Tom &amp; Jerry<style>.x{color:red}</style>"))
+        val converted = HtmlToText.convert("<script>alert('x')</script>Safe")
+        assertEquals("Safe", converted)
+        assertFalse(converted.contains("alert"))
+    }
+
+    @Test
+    fun `collapses excess whitespace`() {
+        val converted = HtmlToText.convert("<p>Hello    there</p>\n\n\n<p>bye</p>")
+        assertTrue(converted.contains("Hello there"), converted)
+        assertFalse(converted.contains("Hello    there"), converted)
+    }
+}
diff --git a/app/src/test/kotlin/org/libremail/mail/SmtpSenderTest.kt b/app/src/test/kotlin/org/libremail/mail/SmtpSenderTest.kt
index 32fa157..52fd553 100644
--- a/app/src/test/kotlin/org/libremail/mail/SmtpSenderTest.kt
+++ b/app/src/test/kotlin/org/libremail/mail/SmtpSenderTest.kt
@@ -61,6 +61,74 @@ class SmtpSenderTest {
         assertTrue(GreenMailUtil.getBody(received[0]).contains("Hello there"))
     }
 
+    @Test
+    fun `a formatted message is sent as multipart alternative with both parts`() = runTest {
+        val params = SmtpParams(
+            host = "127.0.0.1",
+            port = greenMail.smtp.port,
+            security = MailSecurity.NONE,
+            username = "sender@example.org",
+            secret = "secret",
+            useXoauth2 = false,
+        )
+
+        sender.send(
+            params = params,
+            from = "sender@example.org",
+            message = OutgoingMessage(
+                accountId = "x",
+                to = "bob@example.org",
+                subject = "Rich",
+                body = "Hello world",
+                bodyHtml = "<p>Hello <b>world</b></p>",
+            ),
+        )
+
+        greenMail.waitForIncomingEmail(1)
+        val received = greenMail.receivedMessages.single()
+        assertTrue(received.contentType.contains("multipart/alternative", ignoreCase = true), received.contentType)
+        val raw = GreenMailUtil.getWholeMessage(received)
+        assertTrue(raw.contains("text/plain", ignoreCase = true), "missing text/plain")
+        assertTrue(raw.contains("text/html", ignoreCase = true), "missing text/html")
+        assertTrue(raw.contains("<b>world</b>"), "missing html body")
+        assertTrue(raw.contains("Hello world"), "missing plaintext fallback")
+    }
+
+    @Test
+    fun `a formatted message with an attachment nests the alternative inside mixed`() = runTest {
+        val file = File.createTempFile("libremail-note", ".txt").apply { writeText("attached note") }
+        val params = SmtpParams(
+            host = "127.0.0.1",
+            port = greenMail.smtp.port,
+            security = MailSecurity.NONE,
+            username = "sender@example.org",
+            secret = "secret",
+            useXoauth2 = false,
+        )
+
+        sender.send(
+            params = params,
+            from = "sender@example.org",
+            message = OutgoingMessage(
+                accountId = "x",
+                to = "bob@example.org",
+                subject = "Rich + file",
+                body = "Body",
+                bodyHtml = "<p><b>Body</b></p>",
+            ),
+            attachments = listOf(file),
+        )
+
+        greenMail.waitForIncomingEmail(1)
+        val received = greenMail.receivedMessages.single()
+        assertTrue(received.contentType.contains("multipart/mixed", ignoreCase = true), received.contentType)
+        val raw = GreenMailUtil.getWholeMessage(received)
+        assertTrue(raw.contains("multipart/alternative", ignoreCase = true), "missing alternative part")
+        assertTrue(raw.contains(file.name), "missing attachment")
+        assertTrue(raw.contains("<b>Body</b>"), "missing html body")
+        file.delete()
+    }
+
     @Test
     fun `send delivers a message with an attachment`() = runTest {
         val file = File.createTempFile("libremail-report", ".txt").apply { writeText("quarterly numbers") }
diff --git a/app/src/test/kotlin/org/libremail/richtext/RichTextEditingTest.kt b/app/src/test/kotlin/org/libremail/richtext/RichTextEditingTest.kt
new file mode 100644
index 0000000..f0cb15b
--- /dev/null
+++ b/app/src/test/kotlin/org/libremail/richtext/RichTextEditingTest.kt
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.richtext
+
+import org.junit.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class RichTextEditingTest {
+
+    @Test
+    fun `toggleStyle adds then removes a style over the selection`() {
+        val base = RichTextContent("hello")
+        val bold = RichTextEditing.toggleStyle(base, 0, 5, RichStyle.BOLD)
+        assertEquals(listOf(RichSpan(0, 5, RichStyle.BOLD)), bold.spans)
+
+        val plain = RichTextEditing.toggleStyle(bold, 0, 5, RichStyle.BOLD)
+        assertTrue(plain.spans.isEmpty())
+    }
+
+    @Test
+    fun `toggleStyle over a fully styled sub-range removes just that part`() {
+        val bold = RichTextContent("hello", spans = listOf(RichSpan(0, 5, RichStyle.BOLD)))
+        val result = RichTextEditing.toggleStyle(bold, 1, 3, RichStyle.BOLD)
+        assertEquals(
+            listOf(RichSpan(0, 1, RichStyle.BOLD), RichSpan(3, 5, RichStyle.BOLD)),
+            result.spans.sortedBy { it.start },
+        )
+    }
+
+    @Test
+    fun `applyLink links the selection and removes overlapping links`() {
+        val base = RichTextContent("see here")
+        val linked = RichTextEditing.applyLink(base, 4, 8, "http://x")
+        assertEquals(listOf(RichLink(4, 8, "http://x")), linked.links)
+
+        val relinked = RichTextEditing.applyLink(linked, 0, 8, "http://y")
+        assertEquals(listOf(RichLink(0, 8, "http://y")), relinked.links)
+    }
+
+    @Test
+    fun `toggleBlock adds a bullet marker to the caret's line and shifts spans`() {
+        val base = RichTextContent("ab", spans = listOf(RichSpan(0, 2, RichStyle.BOLD)))
+        val result = RichTextEditing.toggleBlock(base, 0, 0, BlockMarker.BULLET)
+        assertEquals("• ab", result.content.text)
+        assertEquals(listOf(RichSpan(2, 4, RichStyle.BOLD)), result.content.spans)
+    }
+
+    @Test
+    fun `toggleBlock numbers each line of a multi-line selection`() {
+        val base = RichTextContent("a\nb\nc")
+        val result = RichTextEditing.toggleBlock(base, 0, 5, BlockMarker.ORDERED)
+        assertEquals("1. a\n2. b\n3. c", result.content.text)
+    }
+
+    @Test
+    fun `toggleBlock removes the marker when every selected line already has it`() {
+        val base = RichTextContent("• a\n• b")
+        val result = RichTextEditing.toggleBlock(base, 0, base.text.length, BlockMarker.BULLET)
+        assertEquals("a\nb", result.content.text)
+        assertFalse(RichTextEditing.hasBlock(result.content, 0, result.content.text.length, BlockMarker.BULLET))
+    }
+
+    @Test
+    fun `toggleBlock replaces a different marker in place`() {
+        val base = RichTextContent("• a")
+        val result = RichTextEditing.toggleBlock(base, 0, 3, BlockMarker.QUOTE)
+        assertEquals("> a", result.content.text)
+    }
+}
diff --git a/app/src/test/kotlin/org/libremail/richtext/RichTextHtmlTest.kt b/app/src/test/kotlin/org/libremail/richtext/RichTextHtmlTest.kt
new file mode 100644
index 0000000..7bf7657
--- /dev/null
+++ b/app/src/test/kotlin/org/libremail/richtext/RichTextHtmlTest.kt
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+package org.libremail.richtext
+
+import org.junit.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class RichTextHtmlTest {
+
+    @Test
+    fun `plain paragraphs become p with br line breaks`() {
+        val html = RichTextHtml.toHtml(RichTextContent("Hello\nWorld"))
+        assertEquals("<p>Hello<br>World</p>", html)
+    }
+
+    @Test
+    fun `inline styles nest as b i u`() {
+        val content = RichTextContent(
+            text = "bold italic under",
+            spans = listOf(
+                RichSpan(0, 4, RichStyle.BOLD),
+                RichSpan(5, 11, RichStyle.ITALIC),
+                RichSpan(12, 17, RichStyle.UNDERLINE),
+            ),
+        )
+        assertEquals("<p><b>bold</b> <i>italic</i> <u>under</u></p>", RichTextHtml.toHtml(content))
+    }
+
+    @Test
+    fun `overlapping styles stay valid html`() {
+        val content = RichTextContent(
+            text = "abcd",
+            spans = listOf(RichSpan(0, 3, RichStyle.BOLD), RichSpan(1, 4, RichStyle.ITALIC)),
+        )
+        // b over [0,3), i over [1,4): every run fully closes its tags, so nesting is always valid.
+        assertEquals("<p><b>a</b><b><i>bc</i></b><i>d</i></p>", RichTextHtml.toHtml(content))
+    }
+
+    @Test
+    fun `bulleted and numbered lists and quotes map to block tags`() {
+        assertEquals("<ul><li>Milk</li><li>Eggs</li></ul>", RichTextHtml.toHtml(RichTextContent("• Milk\n• Eggs")))
+        assertEquals("<ol><li>One</li><li>Two</li></ol>", RichTextHtml.toHtml(RichTextContent("1. One\n2. Two")))
+        assertEquals("<blockquote>a<br>b</blockquote>", RichTextHtml.toHtml(RichTextContent("> a\n> b")))
+    }
+
+    @Test
+    fun `links render as anchors and text is html escaped`() {
+        val content = RichTextContent("a<b>&c", links = listOf(RichLink(0, 1, "http://x?y=1&z")))
+        val html = RichTextHtml.toHtml(content)
+        assertTrue(html.contains("<a href=\"http://x?y=1&amp;z\">a</a>"), html)
+        assertTrue(html.contains("&lt;b&gt;&amp;c"), html)
+    }
+
+    @Test
+    fun `plaintext keeps the readable markers`() {
+        assertEquals("• Milk\n> quote", RichTextHtml.toPlainText(RichTextContent("• Milk\n> quote")))
+    }
+
+    @Test
+    fun `hasFormatting is false for unstyled markerless text`() {
+        assertFalse(RichTextContent("just words\nmore words").hasFormatting())
+        assertTrue(RichTextContent("• bullet").hasFormatting())
+        assertTrue(RichTextContent("x", spans = listOf(RichSpan(0, 1, RichStyle.BOLD))).hasFormatting())
+    }
+
+    @Test
+    fun `fromHtml round-trips paragraphs styles lists quotes and links`() {
+        listOf(
+            RichTextContent("Hello\nWorld"),
+            RichTextContent("bold", spans = listOf(RichSpan(0, 4, RichStyle.BOLD))),
+            RichTextContent("• Milk\n• Eggs"),
+            RichTextContent("1. One\n2. Two"),
+            RichTextContent("> a\n> b"),
+            RichTextContent("see here", links = listOf(RichLink(4, 8, "http://example.com"))),
+            RichTextContent("a<b>&c"),
+        ).forEach { original ->
+            val restored = RichTextHtml.fromHtml(RichTextHtml.toHtml(original))
+            assertEquals(original.text, restored.text, "text: $original")
+            assertEquals(
+                original.spans.sortedBy(RichSpan::start),
+                restored.spans.sortedBy(RichSpan::start),
+                "spans: $original",
+            )
+            assertEquals(
+                original.links.sortedBy(RichLink::start),
+                restored.links.sortedBy(RichLink::start),
+                "links: $original",
+            )
+        }
+    }
+
+    @Test
+    fun `fromHtml tolerates strong em and pretty-printed whitespace`() {
+        val restored = RichTextHtml.fromHtml("<ul>\n  <li>One</li>\n  <li><strong>Two</strong></li>\n</ul>")
+        assertEquals("• One\n• Two", restored.text)
+        // "Two" occupies [8,11) of "• One\n• Two".
+        assertEquals(listOf(RichSpan(8, 11, RichStyle.BOLD)), restored.spans)
+    }
+
+    @Test
+    fun `empty content produces empty html`() {
+        assertEquals("", RichTextHtml.toHtml(RichTextContent("")))
+    }
+}
diff --git a/app/src/test/kotlin/org/libremail/ui/compose/ComposeViewModelTest.kt b/app/src/test/kotlin/org/libremail/ui/compose/ComposeViewModelTest.kt
index a2bda85..c48c499 100644
--- a/app/src/test/kotlin/org/libremail/ui/compose/ComposeViewModelTest.kt
+++ b/app/src/test/kotlin/org/libremail/ui/compose/ComposeViewModelTest.kt
@@ -5,6 +5,7 @@ import androidx.lifecycle.SavedStateHandle
 import io.mockk.coEvery
 import io.mockk.every
 import io.mockk.mockk
+import io.mockk.slot
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -16,16 +17,21 @@ import org.junit.After
 import org.junit.Before
 import org.junit.Test
 import org.libremail.data.settings.AccountSettingsRepository
+import org.libremail.data.settings.SignatureRepository
 import org.libremail.domain.model.Account
 import org.libremail.domain.model.AccountSettings
 import org.libremail.domain.model.AuthType
 import org.libremail.domain.model.Draft
 import org.libremail.domain.model.MailSecurity
+import org.libremail.domain.model.OutgoingMessage
 import org.libremail.domain.model.ServerConfig
+import org.libremail.domain.model.Signature
 import org.libremail.domain.repository.AccountRepository
 import org.libremail.domain.repository.MailRepository
 import org.libremail.ui.navigation.Routes
 import kotlin.test.assertEquals
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
 
 @OptIn(ExperimentalCoroutinesApi::class)
 class ComposeViewModelTest {
@@ -48,10 +54,14 @@ class ComposeViewModelTest {
         smtp = ServerConfig("smtp.example.org", 465, MailSecurity.SSL_TLS),
     )
 
+    private fun signature(accountId: String, html: String) =
+        Signature(id = "$accountId:sig", accountId = accountId, name = "Signature", html = html, isDefault = true)
+
     private fun viewModel(
         accounts: List<Account> = listOf(alice),
         savedState: SavedStateHandle = SavedStateHandle(),
-        signatures: Map<String, AccountSettings> = emptyMap(),
+        signatures: Map<String, Signature> = emptyMap(),
+        settings: Map<String, AccountSettings> = emptyMap(),
         mailRepository: MailRepository = mockk(relaxed = true),
     ): ComposeViewModel {
         val accountRepository = mockk<AccountRepository>()
@@ -59,22 +69,36 @@ class ComposeViewModelTest {
         val accountSettingsRepository = mockk<AccountSettingsRepository>()
         coEvery { accountSettingsRepository.get(any()) } answers {
             val id = firstArg<String>()
-            signatures[id] ?: AccountSettings(id)
+            settings[id] ?: AccountSettings(id)
         }
+        val signatureRepository = mockk<SignatureRepository>()
+        coEvery { signatureRepository.getDefault(any()) } answers { signatures[firstArg<String>()] }
         return ComposeViewModel(
             savedStateHandle = savedState,
             mailRepository = mailRepository,
             accountRepository = accountRepository,
             contactsRepository = mockk(relaxed = true),
             accountSettingsRepository = accountSettingsRepository,
+            signatureRepository = signatureRepository,
         )
     }
 
     @Test
-    fun `appends the sending account signature to a new message`() = runTest(testDispatcher) {
-        val vm = viewModel(signatures = mapOf("imap:a" to AccountSettings("imap:a", signature = "Cheers, Alice")))
+    fun `appends the sending account default signature to a new message`() = runTest(testDispatcher) {
+        val vm = viewModel(signatures = mapOf("imap:a" to signature("imap:a", "Cheers, Alice")))
 
         assertEquals("\n\n-- \nCheers, Alice", vm.state.value.body)
+        // A plain signature carries no formatting, so the message stays plaintext-only.
+        assertNull(vm.state.value.bodyHtml)
+    }
+
+    @Test
+    fun `a rich signature makes the new message carry an HTML body`() = runTest(testDispatcher) {
+        val vm = viewModel(signatures = mapOf("imap:a" to signature("imap:a", "Cheers, <b>Alice</b>")))
+
+        assertEquals("\n\n-- \nCheers, Alice", vm.state.value.body)
+        val html = vm.state.value.bodyHtml
+        assertTrue(html != null && html.contains("<b>Alice</b>"), "html=$html")
     }
 
     @Test
@@ -82,8 +106,8 @@ class ComposeViewModelTest {
         val vm = viewModel(
             accounts = listOf(alice, bob),
             signatures = mapOf(
-                "imap:a" to AccountSettings("imap:a", signature = "Cheers, Alice"),
-                "imap:b" to AccountSettings("imap:b", signature = "Best, Bob"),
+                "imap:a" to signature("imap:a", "Cheers, Alice"),
+                "imap:b" to signature("imap:b", "Best, Bob"),
             ),
         )
         assertEquals("\n\n-- \nCheers, Alice", vm.state.value.body)
@@ -93,6 +117,16 @@ class ComposeViewModelTest {
         assertEquals("\n\n-- \nBest, Bob", vm.state.value.body)
     }
 
+    @Test
+    fun `does not append a signature when the account disabled it`() = runTest(testDispatcher) {
+        val vm = viewModel(
+            signatures = mapOf("imap:a" to signature("imap:a", "Cheers, Alice")),
+            settings = mapOf("imap:a" to AccountSettings("imap:a", signatureEnabled = false)),
+        )
+
+        assertEquals("", vm.state.value.body)
+    }
+
     @Test
     fun `does not append a signature when resuming a draft`() = runTest(testDispatcher) {
         val mailRepository = mockk<MailRepository>(relaxed = true)
@@ -104,14 +138,32 @@ class ComposeViewModelTest {
             subject = "Hi",
             body = "Draft body",
             updatedAt = 0L,
+            bodyHtml = "<p>Draft <b>body</b></p>",
             attachments = emptyList(),
         )
         val vm = viewModel(
             savedState = SavedStateHandle(mapOf(Routes.COMPOSE_ARG_DRAFT to "d1")),
-            signatures = mapOf("imap:a" to AccountSettings("imap:a", signature = "Cheers, Alice")),
+            signatures = mapOf("imap:a" to signature("imap:a", "Cheers, Alice")),
             mailRepository = mailRepository,
         )
 
         assertEquals("Draft body", vm.state.value.body)
+        // The draft's HTML body is restored so it round-trips back out on send.
+        assertEquals("<p>Draft <b>body</b></p>", vm.state.value.bodyHtml)
+    }
+
+    @Test
+    fun `send carries the HTML body through to the outgoing message`() = runTest(testDispatcher) {
+        val mailRepository = mockk<MailRepository>(relaxed = true)
+        val sent = slot<OutgoingMessage>()
+        coEvery { mailRepository.sendMessage(capture(sent)) } returns Result.success(Unit)
+        val vm = viewModel(mailRepository = mailRepository)
+
+        vm.onToChange("bob@example.org")
+        vm.onBodyChange("Hello", "<p>Hello <i>world</i></p>")
+        vm.send()
+
+        assertEquals("<p>Hello <i>world</i></p>", sent.captured.bodyHtml)
+        assertEquals("Hello", sent.captured.body)
     }
 }