Back in 2006, when I set up thinktank.co.nz’s mail server defenses, SPAM was increasing at an astronomical rate. There were a number of tools to use on mail servers to help stem the tide, including greylisting, SpamAssassin, Realtime Blackhole Lists (RBL’s), signature systems including Vipul’s Razor and Pyzor; other technologies such as Sender Policy Framework…