Mail Quota with Dovecot (User + Domain)

[kilburn]

Domain quotas and mail quotas are different beasts. Mail quotas (which ispcp doesn't directly support as of now) are to be checked each time a mail is delivered, whereas domain disk quotas are updated just overnight.

Thus, integrating them both in the mail delivery is a fairly stupid thing to do, because if the domain is ever detected over-quota, all the users would be unable to receive e-mails for a whole day, even if they free the overused space.

That said, the short answer is: trying to check domain quotas when delivering mail is currently a stupid thing to do, so just make sure that sum(mail_quotas) < domain_quota and you'll be fine.