Re: [Dovecot] what best for anti-spam filter?

24.07.2012 11:57, Arnaud Abélard:

• With greylisting we aren't rejecting potentially spammy mails, we are rejecting misbehaving servers. That's important, legally speaking. We could be in trouble if we rejected an important mail by mistake when our server actually accepted it.

That's something which is not greylisting-specific at all. You must not accept mail you are unwilling or unable to deliver - ever! Creating bounces will make you a source of backscatter and get you blacklisted, eventually. ("Outgoing" mail is a different matter, of course)

But that doesn't mean that greylisting is the only means for fighting spam that is compliant to the above rule. It's, for example, not uncommon to have things like milters or pre-queue filters pipe the incoming mail through a spam checker and accept or reject the mail - during the SMTP dialogue - depending on the result of the check.

-- Regards mks