Introduction

When Roundcube sends mail but nothing shows up in the Sent folder after a server move, the problem is usually not the message itself. In most cases, the message was sent successfully and the failure is in how Roundcube or the IMAP server maps, subscribes to, or stores the sent-mail copy on the new server. Migrations often change folder names, namespaces, delimiters, or special folder detection, so Roundcube keeps looking for the old Sent path while the new server saves mail somewhere else.

Treat this as a sent-folder mapping problem before assuming mail is being lost. This issue is particularly common after mail server migrations, moves between different IMAP backends (Dovecot, Courier, Cyrus), or when migrating from cPanel to Plesk or other hosting platforms. The Roundcube configuration or user preferences may still reference folder paths from the old server that don't exist or don't match on the new server.

Understanding that Roundcube relies on IMAP folder subscriptions and special folder detection helps troubleshoot this issue. The application needs to know which folder to save sent messages to, and this mapping can break when the server-side folder structure changes during migration.

Symptoms

  • Messages send successfully from Roundcube, but no copy appears in Sent folder
  • Old sent mail is visible, but new sent messages do not show up after the server move
  • Roundcube shows multiple possible Sent folders such as Sent, Sent Items, or INBOX.Sent
  • The issue appeared right after migration, server replacement, or mail platform change
  • Another mail client (Outlook, Thunderbird) shows the sent copy in a different folder than Roundcube
  • Only some mailboxes are affected while others still save to Sent normally
  • Sent folder appears empty even though messages are being sent successfully
  • Users report sent messages not appearing in their Sent items
  • Test messages arrive at recipients but no record in Roundcube Sent folder
  • Folder list shows different folder names than before migration

Common Causes

  • Roundcube is still mapped to the old Sent folder path from the previous server
  • The correct Sent folder exists but is not subscribed in IMAP after migration
  • The new IMAP server uses a different namespace, delimiter, or special-use folder configuration
  • A second Sent-style folder was created during migration and Roundcube is reading the wrong one
  • The mailbox can send mail, but the IMAP folder lacks the right permissions or write behavior
  • Cached Roundcube preferences or old folder metadata survived the server move
  • Special folder auto-detection failed on the new server
  • Folder delimiter changed (dot vs slash) breaking path references
  • IMAP ACL or permissions prevent Roundcube from saving to the Sent folder

Step-by-Step Fix

  1. 1.Send a fresh test message from Roundcube and confirm whether the message is actually delivered to the recipient, because if delivery works but the sent copy is missing, you can focus on folder mapping instead of outbound mail transport.
  2. 2.Open Roundcube settings (Settings > Preferences > Special Folders) and verify which folder is assigned as the Sent folder for that mailbox, because migrations often leave Roundcube pointing to the old folder name even after the server now uses a different path.
  3. 3.Compare the visible folder list for duplicates such as Sent, Sent Items, INBOX.Sent, or localized folder names, because a server move can create a second folder that holds the new sent copies while Roundcube keeps displaying the old one.
  4. 4.Check IMAP subscriptions for the mailbox (right-click folder list > Manage Folders or Settings > Folders) and subscribe the correct Sent folder if needed, because Roundcube can fail to display the active folder cleanly when the mailbox copy exists but the folder was never subscribed after migration.
  5. 5.Verify the IMAP namespace and folder delimiter on the new server using an IMAP client or command line, because a mailbox that used to store Sent under one path style (INBOX.Sent) can move to another (Sent) and break the folder mapping Roundcube saved previously.
  6. 6.Confirm the mail server is marking or exposing the correct special-use sent folder in its IMAP configuration (Dovecot special_use setting), because Roundcube relies on the server-side folder model more reliably when the new platform advertises the right Sent mailbox instead of leaving multiple candidates.
  7. 7.Check mailbox permissions, quota state, and ownership if the server should save a sent copy but does not, because a folder that cannot be written to cleanly can make Roundcube appear to send mail without ever storing the message in Sent.
  8. 8.Clear stale Roundcube preferences or test the same mailbox with a clean Roundcube session (different browser or clear browser data) if the mapping still looks wrong, because cached folder settings from the old server can survive the migration and keep forcing the wrong Sent folder.
  9. 9.Re-test from Roundcube and from another IMAP client (Thunderbird, Outlook) after each change and document which folder receives the sent copy, because matching behavior across clients confirms the mailbox mapping is fixed while a mismatch points to a client-specific Roundcube problem.

Verification

Confirm the fix is complete:

  1. 1.Send a test message from Roundcube and verify it appears in the Sent folder
  2. 2.Check that the sent message shows correct timestamp and recipient
  3. 3.Test with another IMAP client to confirm sent messages appear in the same folder
  4. 4.Verify old sent messages are still accessible
  5. 5.Check that new sent messages are saved consistently going forward

Prevention

To avoid this issue in future migrations:

  • Document folder paths and namespace settings before migration
  • Test Roundcube functionality immediately after migration, not just mail delivery
  • Verify special folder mapping is correctly detected by Roundcube post-migration
  • Check folder subscriptions are preserved or restored after migration
  • Consider using a consistent IMAP namespace across server migrations
  • Document the Sent folder location in migration runbooks
  • Test with multiple mail clients to verify consistent folder structure
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