Dovecot doesn't work too well with filesystem quota currently. But there are a few things you can do:
- Set index file location to some partition where there are no quota limits. Dovecot can't currently handle out-of-quota error conditions when updating indexes.
mbox should work somewhat nicely as long as mbox_lazy_writes=yes in config file. Although if user doesn't delete any mails when closing the mailbox, Dovecot gives an "internal error".
Maildir also needs to update dovecot-uidlist file, which can't handle out-of-quota errors. Its location can be set using "CONTROL" parameter in default_mail_env.
So, use something like:
# mbox: default_mail_env = mbox:%h/mail:INBOX=/var/mail/%u:INDEX=/var/no-quotas/index/%u # maildir: default_mail_env = maildir:%h/Maildir:INDEX=/var/no-quotas/index/%u:CONTROL=/var/no-quotas/control/%u
Dovecot 1.0 supports quota using a quota plugin. It's currently discussed in [wiki:LDA Dovecot LDA] page and it supports only very simple quota calculation which is suitable only for mboxes. Maildir++ quota support will come later.