Looking for a concise guide to the Exchange 2003 anti-spam features? The following Technet presentation covers both the Intelligent Message Filter (IMF) and the Exchange 2003 out-of-the-box anti-spam protocol filtering capabilities. The content is straight to the point with no frills.
Approach to Fighting Spam in an Exchange Environment
On the same subject a series of three webcasts is also available. These present the same information but in a much less concise manner in my opinion. As an extra penalty you have to registering for the events. Here are the links to the webcasts if you want to judge for yourselves.
TechNet Webcast: Approaches to Fighting Spam in an Exchange Environment (Part 1 of 3)-Level 200
TechNet Webcast: Approaches to Fighting Spam in an Exchange Environment (Part 2 of 3)-Level 200
TechNet Webcast: Approaches to Fighting Spam in an Exchange Environment (Part 3 of 3)-Level 200