I’ve now installed and activated Postgrey, a Postfix policy service that implements “greylisting”.

So any email coming into csamuel.org for any email address hosted here will get a “try again later” message, the sending email server should retry it later. Spammers on the other hand usually try once and then move on because they’ve got so much email to send.

If you see any email rejected from csamuel.org, auties.org or donnawilliams.net because of this please email the user Postmaster, who won’t have this test applied

This is a pretty impressive graph from the guy who wrote Postgrey to show what happened when he activated it for him on the Tuesday.