Given the marked rise in spam over the past few months, it’s time to reneg on a long-standing decision to defer RBL filtering to SpamAssassin. Effective immediately if a sender’s IP address is listed in SpamHaus, then it will be rejected by the MTA.
The only change now is that SpamAssassin won’t be performing SpamHaus lookups, but rather Postfix will. This should help cut down on spam that slips through due to poor bayes scoring.
RBL filtering in place – SpamHaus