SPAM Filter

[JP]

I use open source software.

http://www.spampal.org

does a great job for me since june 2003.
requires using the training mode for some time, but it keeps great logs/stats.
I also still have to add certain ones to the whitelist.

it comes with plenty of plugins like badwords, baysian filter, regEx filter, urlbody detection and you can filter email servers by country (most comes from china, malaysia, russia...where most webmasters dont do biz with anyways, and those few partners there you could whitelist by email or their email server IP range).
it is somewhat like spamassassin (linux, used by many ISPs) just that this runs on any version of windows and works for any type of pop3/imap mail application like Outlook (dont use that unless you want to be exploited!), eudora or pegasus mail (i use that).

you get weekly update notifications. it's free, works great and always is updated and u can tweak it to your own needs through an easy windows interface.