Postfix to reject unknown adresses
I've been "tail -f"-watching the mail.log a bit and I'd like to know if there's a way to let postfix reject incoming messages along a configuration (hash) file that contains all valid adresses, which would have to be generated by ISPConfig. I believe this would be an extra value for the "smtpd_recipient_restrictions" parameter, like "check_recipient_access". I would let this value kick in beofre or after greylisting, which ever would be more clever.
The result would be something like "550 recipient doesn't exist here" for any non-existing mailbox or alias (or 450... I didn't really read/understand the RFC2821).
My question: is ISPConfig able to provide such a hash file?
If yes: how?
If no: could this be made a feature request?