Corporate Guardian 6

SmoothWall's Corporate Guardian 6 is a software-based offering that is unique in that the product runs on a hardened version of Linux. The software provides a number of features and uses most of the common techniques to detect and block spam. These include using blacklists, heuristics and learning from legitimate incoming email. A feature that is quite handy for smaller organisations with outsourced hosted email is the ability for the spam filter to screen incoming POP3 traffic in addition to the traditional SMTP filtering.