I am a big fan of the Exchange 2003 SP2 Intelligent Message Filter. It is *free* and *easy* to configure. For small and medium sized businesses that don't want to invest in separate SMTP message hygiene systems or perimeter SMTP gateways, it is a good solution. I find that the IMF reduces about 95% of the spam I receive in my Inbox. 95% is a good percentage for a free spam filter. I usually configure it to block anything with an SCL of 7 or higher and put anything with an SCL of 5 or higher in my Junk E-mail folder.However, the IMF is just not very tune-able. That is why I like   read more »