Problem Description
Those trying to email you are unable to get through and receive a bounce with the following error text:
Action: failed
Status: 5.7.1
Diagnostic-Code: x-unix; Message can't be delivered
This occurs because your mailbox is full.
Problem Resolution
To resolve this problem, please log in via webmail and delete older and/or larger messages or use Thunderbird to archive them to your computer locally, then remove them from the server. Once the mailbox is no longer full emails will be able to reach you again and those sending messages to you will no longer receive bounces.