fix: restore deleted_at mails when still on IMAP server — sync was permanently hiding mails

- When IMAP delete fails, deleted_at stays set but mail remains on IMAP server
- Sync was skipping deleted_at mails, so they stayed permanently hidden
- Now sync restores deleted_at=None when mail is found on IMAP server
- This means: if IMAP delete fails, mail reappears in LeoCRM on next sync
- Only truly deleted mails (removed from IMAP server) stay hidden

app/plugins/builtins/mail/services.py

@@ -662,9 +662,12 @@ async def imap_sync_folder(
                         ).scalar_one_or_none()
 
             if existing_mail:
-                # Don't touch soft-deleted mails — they're being deleted via sync queue
+                # If mail has deleted_at but is still on the IMAP server,
+                # the IMAP delete failed — restore it so it's visible again.
+                # This prevents mails from being permanently hidden when IMAP delete fails.
                 if existing_mail.deleted_at is not None:
-                    continue
+                    existing_mail.deleted_at = None
+                    logger.info("imap_sync_folder: restored mail %s (still on IMAP server, delete had failed)", existing_mail.id)
                 # Update folder_id and imap_uid if mail moved to a different folder
                 if existing_mail.folder_id != folder.id:
                     existing_mail.folder_id = folder.id
@@ -1157,9 +1160,11 @@ async def imap_sync_account(
                         ).scalar_one_or_none()
 
                     if existing_mail:
-                        # Don't touch soft-deleted mails — they're being deleted via sync queue
+                        # If mail has deleted_at but is still on the IMAP server,
+                        # the IMAP delete failed — restore it so it's visible again.
                         if existing_mail.deleted_at is not None:
-                            continue
+                            existing_mail.deleted_at = None
+                            logger.info("imap_sync_account: restored mail %s (still on IMAP server, delete had failed)", existing_mail.id)
                         # Track folder moves: update folder_id and imap_uid if the
                         # mail now appears in a different IMAP folder.
                         if existing_mail.folder_id != folder.id: