I wasn't surprised to hear that Microsoft has been working on antispam technology for some time now; after all, the company's MSN Hotmail, MSN, Microsoft Exchange Server, Microsoft Outlook, and Outlook Express products are some of the most popular email services, servers, and applications on the planet. But in a meeting this week at COMDEX, I was surprised to hear that Microsoft Research first began actively looking at antispam technology as far back as 1997 and has numerous antispam patents. Microsoft's antispam technology is based on a concept called machine learning, in which you feed a known set of bad email messages to a database, run the database through the antispam technology's filters, and configure the database to continually learn what is and isn't legitimate email, letting it become more accurate over time to keep up with spam makers' changing strategies. And if you're wondering how effective this technology is, consider Microsoft's test cases: Hotmail email servers process millions of spam messages every day.