Microsoft has spent several years working on antispam technology, and beginning in 2003, we finally started seeing some results, including a new spam filter that debuted in the company's MSN Hotmail and MSN 8 mail servers. In late 2003, Microsoft added this technology, dubbed SmartScreen Technology, to its Microsoft Office Outlook 2003 email and personal information manager (PIM) client. The company also announced plans to make the technology available to certain Microsoft Exchange Server 2003 customers through a new add-on called the Exchange Intelligent Message Filter. Here's what you need to know about SmartScreen Technology and the Exchange Intelligent Message Filter.

Microsoft Targets Spam
Developed by Microsoft Research, SmartScreen Technology is based on Bayesian-like machine learning technology that uses a probability-based algorithm to determine whether email is legitimate or spam. The technology learns over time which email messages are legitimate and gets better the more you use it.

To help make SmartScreen Technology more effective, Microsoft tested it on millions of email messages delivered through the company's Hotmail email filters, asking thousands of users to rate the messages as legitimate or spam. Based on the responses, Microsoft put the email messages in a database used to train SmartScreen Technology. Basically, the technology evaluates the contents of each email message and assigns a weighted score to each message according to more than 500,000 characteristics; the higher the score, the higher the probability that the message is spam.

Administrators who roll out the Exchange Intelligent Message Filter can determine where to draw the line between what is and isn't spam and can let individual users set their own ratings system, if desired. Microsoft believes that combining the Exchange Intelligent Message Filter with the client-side antispam features in Outlook 2003 and an intelligent network-edge filter, such as the one in Microsoft Internet Security and Acceleration (ISA) Server 2004 (which includes HTTP spam-filtering capabilities for companies that opt to use Exchange 2003's HTTP capabilities), will provide the most effective means to combat spam.

Who Qualifies for the Exchange Add-On?
Initially, the Exchange Intelligent Message Filter will be available only to Microsoft Software Assurance (SA) customers, so you must take part in Microsoft Open License 6.0 to take advantage of this feature. However, the add-on is otherwise free.

Recommendations
If you're an SA customer running Exchange 2003, you should start evaluating this valuable technology. The Exchange Intelligent Message Filter doesn't need to replace any other mail-filter technology you might be using and can instead work in a complementary fashion with other antispam products. Given the price and value of this software, the Exchange Intelligent Message Filter is a must-have upgrade for qualifying Exchange 2003 users.