Thank you for the refference.
Yes i already checked the policyd web page and  have no problem with setting it up that way.
However it would be great to have the possibility to automatically add all non-existing mail users as spam traps.
I mean, when a recipient mail address is not found on my server, it would be handled as spamtrap and sender would be marked as spam source candidate. If no more emails would come to any of the defined spam traps in a given time (like 4 hours), that sender would be cleared from spam candidates (to avoid blocking senders who just typo-ed the email address) and if more emails would come to any of the spamtraps, it would be confirmed as spam source and blocked (with a high spam score, possibly configurable).