Slow or incomplete IMAP sync is usually caused by oversized folders, local client corruption, unstable connections, or a misconfigured IMAP root path.
Common symptoms
- Sent items or custom folders are missing
- The client downloads mail very slowly
- One device shows folders that another device does not
Troubleshooting steps
- Confirm the mail client is configured to use IMAP rather than POP if folder sync is expected across devices.
- Check mailbox usage and reduce oversized folders by archiving or deleting unnecessary mail.
- Force a folder list refresh or resubscribe to missing folders in the mail client.
- Test from webmail to confirm the folders exist on the server and were not deleted locally.
- If only one device is affected, recreate the mail profile on that device.
Additional notes
- POP does not sync folders in the same way as IMAP and often causes confusion.
- Very large mailboxes can take substantial time to index on first sync.
When to contact support
Contact support if the folders exist in webmail but fail to appear on multiple IMAP clients.