GateWall Antispam supports several spam filtering methods, including DNS filtering (DNSBL, RHSBL, Backscatter, MX, SPF, SURBL), online service filtering ("Cloud Antispam") and statistical filtering (Bayesian filtering method designed by Entensys). In addition, GateWall Antispam supports SMTP monitoring (ensures the commands comply with RFC), allows to set maximum message size, maximum number of addressees, etc.
Spam filtering modules can be configured in a separate directory of the administrator console. When installed, GateWall Antispam already lists the most popular servers to be scanned for spam.