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Microsoft applies its might to fighting spam

David Coursey AnchorDesk

Published: 28 Oct 2003 15:10 GMT

After the MSN member makes the choice, the message is dumped into an adaptive learning system that continually asks the questions: What is it about this message that caused it to be labeled "spam"? And what is it about this message that caused it to be labeled "not spam"?

Those questions have so far been asked about millions of emails, and the answers have helped define some 100,000 variables that can be used to decide whether a given message is likely to be spam.

Hamlin gets a little quiet when asked exactly how this works. What he did say is this: when Outlook receives an incoming message, it is tested against these 100,000 criteria and given a score. If the score is too high, into the junk mail folder it goes. If you're really interested in how this process works, Microsoft has filed for or received some 40 patents in this area, Hamlin told me.

Even if I really understood how all this works, I wouldn't tell you -- for the same reason I won't share the few homeland security secrets I actually do know. I want the defence to keep working, and the bad guys don't deserve a break.

So as spammers figure out ways to get past the Microsoft filter (and I've already discovered one), Microsoft will use its ongoing message analysis to catch the leak in the filter mechanism and plug it.

For MSN users, this is an automatic process that occurs on the MSN mail servers. For Outlook and Exchange users, there are still some issues to be ironed out; because the filtering takes place at the client desktop, filter updates must be applied to every machine.

(As a technical aside, Outlook 2003 spam filtering requires Exchange cached mode to be turned on. This causes messages to be delivered to the client desktop for filtering rather than stored only on the server.)

Microsoft says it wants to update the client filter every 6 to 12 weeks. What doesn't exist -- well, it does, but it's never been used this way -- is a way to distribute these updates to users.

Many people are aware of Windows Update, which can be used to automate the process of updating Microsoft's operating system. There is also something called Office Update for updating the MS Office applications, though it is not automatic.