I see this is a very common problem. Sometimes people get an error on their IMAP webmail connection and checking the log files at /var/log/maillog there’s an error indicating the disk quota for that user.
Jul 2 11:08:51 mail dovecot: imap(email@example.com): Error: user firstname.lastname@example.org: Initialization failed: Initializing mail storage from mail_location setting failed: mkdir(/home/someuser/imap/somedomain.com/mailaccount/Maildir) failed: Disk quota exceeded
The generally people claim that playing around with the disk quota of the user helps it. Interestingly in my case, only setting the quota to “Unlimited” solved the problem. So keep that in mind.
It seems like the reason behind this error is that dovecot used to handle quotas using the /var directory, but now switched it to the /home directory.
Also if somehow your system starts reading quotas wrong, don’t forget to use this little tip : http://www.directadmin.com/features.php?id=529
echo “action=rewrite&value=quota” >> /usr/local/directadmin/data/task.queue
This command will go through each user, and set the quota limits in the system quotas. Users will unlmited quotas will also have their quota limit set to 0 (unlimited).
echo “action=rewrite&value=quota&user=bob” >> /usr/local/directadmin/data/task.queue
Same thing, except it’s just sets the quota for one user.