How ever, a quick look at the mimedefang page tells me you want to do something like
if($hits > 15) return action_discard();
or something similar after calling the spamassassin check routine.
Yes, that's the way to do it. Alternatively you can use action_bounce(), which despite its name will issue an SMTP reject.
Even better would be to call action_quarantine_entire_message first, so that you still have a record in the event of a false positive.
-- Kelson Vibber SpeedGate Communications <www.speed.net>
