Sinapsi Antispam 3.0 is a fully featured freeware Anti-Spam software for Outlook, Outlook Express, Mozilla Thunderbird and now also FreePops.

Main features of this application include:

-Protection based on MD5 Algorithm.
-Soundex Heuristic Analysis.
-Public DNS-BL (Blacklist) IP Filters like dnsbl.org
-OCR (Optical Character Recognition) based Heuristic Analysis.
-BlackList and WhiteList protection.
-Advanced Statistics

It is compatible with Windows 98/ME/NT/2000/XP/2003 Server

Download here