[ILUG] Recurring email problem

[Kevin Philp]

I have a user who has a recurring problem:

They run a Ubuntu client running Thunderbird as the email client and 
have a Dovecot IMAP account on our server where they file their email. 
This is the same setup as everyone else in the office but every couple 
of days their email system jams when it tries to save email to the sent 
folder - which is on the Dovecot System. The mail gets sent but it just 
can't access the sent folder. At the same time the users loses the 
ability to move email from one folder to another. It happened this 
morning - we rebooted the client and everything is back to normal. But 
it will doubtless come back in a couple of days.

I only get this on one computer - it never happens on any of the other 
clients. The other clients continue working fine even when this 
particular one is jammed.

Any suggestions?

Kevin.