I have been running my own Windows Server for over 5 years now, and one of the things I've always been running on it was Exchange Server. I've always loved the ability to have full Exchange functionality for my desktop, laptop, and mobile device keeping them all in sync and having e-mail as it arrives at the server. The one thing that always has proved a pain was Exchange's lack of a comprehensive SPAM filtering feature. Sure you could always manually plug in domains and addresses into its filtering, or in Exchange 2003 SP2 you could enable Intelligent Message Filtering on level of 1 to 8. Enabling Intelligent Message Filtering was practically a useless endeavor, especially if you've been added to various SPAM lists as you would either not get mail you expected, or SPAM would get through like water in a damn with a substantial leak.
In my predicament I decided to try Microsoft Antigen for Exchange, which is part of the Forefront Security Initiative at Microsoft for server security. I was at first somewhat skeptical, given the solutions that Microsoft had provided me before for "stopping" SPAM, but as soon as I installed it I really began to notice the difference immediately. All unwanted email was being stopped by Antigen service and my inbox was amazingly clean. Ever being the skeptic and thinking it may have been eating my good mail too, I decided to poke around the Antigen Administrator and found all of the purged or marked mail under the Quarantine section of the Report tab. Amazing! Not one mail in the quarantine list was actually meant for me. In addition to the elation I was feeling that I had a solution that actually worked, I was also somewhat impressed by the fact that Antigen uses 5 virus scanning engines from major manufacturers such as Computer Associates. Because I'm not really concerned with performance on a server running only a few mailboxes, I have the bias set for Maximum Certainty which processes all emails through all 5 of the virus scanning engines.
Overall I would have to say that Microsoft Antigen for Exchange is a great product for anyone that operates an Exchange Server. I would actually like to see it bundled in future editions of Microsoft Small Business Server, as I feel that the Small Business Market is completely under-served by Microsoft in SPAM and Virus protection in an area where they market SBS an all-in-one solution.