mxORB 

mxORB is a server-side spam filter that consistently blocks over 98% of unsolicited commercial email (also known as spam) at a fraction of the cost of other filtering solutions.
exchange 2000 spam filter exchange 2003 spam filter exchange spam filter exchange iis smtp uce spam filter open relay blacklist event

SpamWeed Anti-Spam Filter 

A powerful & easy-to-use spam filter that blocks over 95% spam instantly for Outlook, OE & other email clients. Spam are placed in a quarantine area & can be retrieved or deleted. SpamWeed learns from mistakes & its detection rate improves with use.
spam spam filter anti spam spam killer spam blocker spam email block spam anti spam software spam software spam mail email spam filter spam inspector spam protection spam stopper