This is the error I get

There was a problem logging onto your mail server. Your Password was rejected. Account: ' ', Server: 'mail.yourwebsite.com', Protocol: POP3, Server Response: '-ERR [IN-USE] Couldn't sync mailbox.', Port: 110, Secure(SSL): No, Server Error: 0x800CCC90, Error Number: 0x800CCC92

This is the cure

You ran out of disk space on your website account. You need to delete files in your website to make room for the emails or you need to upgrade to a larger hosting plan with more space for both emails and website.