Unable to delete emails via Webmail :: Server Error: UID MOVE: Internal error occurred - incorrect permissions

Symptoms

When trying to delete emails from Roundcube or view certain folders, you receive the following error:

Server Error: UID MOVE: Internal error occurred. Refer to server log for more information.

Description 

These errors in Roundcube are reflections of errors from Dovecot when accessing files associated with the emails within your accounts. The Dovecot log will have more information about the specific issue causing the errors. 

Workaround

Search the Dovecot log for more information concerning the errors:

[root@server ~]# grep "Error: Mailbox" /var/log/maillog
Error: Mailbox INBOX.Sent: open(/home/user/mail/domain/emailuser/.Sent/cur/email-file-ID) failed: Permission denied (euid=1000(user) egid=1000(user) missing +r perm
[root@server ~]#

The above error indicates that the permissions for the mail files are incorrect. These will need to be corrected to proceed.

Warning: File maintenance is a task that is best performed by a System Administrator to minimize the risk of causing further issues or data loss. The instructions below are provided as a guide.

1. Connect to the server using SSH or the File Manager
2. Navigate to the affected folder. In the error from the example, it is the ".Sent" folder of the email address that is showing the error and the "cur" folder within it

   cd /home/cpaneluser/mail/domainname/emailuser/.Sent/cur

3. Correct the permissions of all files within this folder by setting the access permissions and proper file ownership. Please make sure to change "$cpaneluser" to your actual cpanel username for the account:

   chown $cpaneluser.$cpaneluser *

   chmod 640 *

Additional Info

System Administration Services