> I wonder if it's possible (easy) to send back 5xx error for mail whose
> envelopes don't match known list patterns, and just to accept (and drop)
> mail who is spam from a list.  SM8.9 does have a $#drop mailer....

Sure, it's possible, but the problem is that for policy reasons, some
mailing lists do not attempt to reject spam.   If the mailing list
administrator bears the pain of this policy, the policy will change.
As long as it's the users getting screwed, forget it.

			       _MelloN_