Restructure isConnectionDrop as leading guard clauses (definite-drop types, then a not-MessagingException early return) instead of a when expression, per maintainer review feedback on PR #368. Behavior is unchanged; verified by the existing ImapConnectionCacheTest suite (all 8 cases still pass), including the FolderClosedException / StoreClosedException cases that depend on the check running before the MessagingException .cause guard. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>