TL;DR: can I
DISCARD outgoing mail to a specific server by DNS name of the MX record , or failing that, by its IP?
We've some 'trouble' (well, more of an annoyance really), of people filling out some random keyboard strokes as e-mail address. Suprise surprise: most of those @hjk.tld & @asdf.tld domains are parked domains for sale. Generally, per tld, there are only 1 to 3 players having claimed the bulk of these domains. Usually, they've configured the same MX record for those domains, but are either not listening on it or denying sending any e-mail on it.
Those e-mails just hang there in the queue, will never be delivered, and bounce back after a the final time-out. That server has better things to do, so I'd like to discard those e-mails immediately. I could list every single one of those domains in a blacklist, but (a) that would mean that when the domain actually is sold / becomes active, mail is discarded unjustly and (b) maintaining that list is a pain.
What I would very much like, is a way in Postfix to list any mail for which the mx server is 'some-mx.somedomainparker.tld' as a reason to discard the mail at the first possible point. If it can't be done based on DNS name, perhaps based on its IP. I can't seem to find anything like that in de docs. Of course, I could just drop traffic to the specific IP, keeping resources used to a minimum, but I'd like to keep my queues as clean as possible.