When a user exceeds his/her storage, an e-mail client may incorrectly report zero e-mails present in the Mailbox.
The mail server/Mail Delivery Agent - Dovecot, uses a cache files to speed up mailbox access for E-Mail clients.
Running out of Disk-Quota/Space can interfere with proper operation of this mechanism.
- Login to the Control Panel
- Check User > Manage Users to verify sufficient storage space is available (increasing limits if required)
- Navigate to Files > Filemanager and visit the Users Home Directory ( /home/<username> )
- Go to the Users Mailbox ( a folder named Mail/ )
- Delete the files: dovecot.index and dovecot.index.log and dovecot.index.cache