Currently if user is 1MB under quota and someone tries to deliver mail that is over 1MB, Dovecot rejects the mail. But smaller mails aren't rejected probably for days. So user might not even realize that they didn't receive one of the mails. Also having a user "almost over quota" is a rather strange state I think.
So what do you think about v2.2 allowing delivery of one last mail even if it brings the user over quota? Except add a limit that if the message size is as much as the user's entire quota limit it wouldn't be added (or 50% or ..?). Also IMAP wouldn't allow this, since user would get an error anyway. I could make this also optional, but if nobody really wants to keep the old behavior there's really no point in adding the option.
