Philoneist checked his Hotmail account yesterday, used only for occasional commercial transactions and professional subscriptions, and found 1100 new messages. Shouldn't it be easier to catch a message from "Amber-Lynn" with the subject "--==LetsDoIt==--"?

Yes, according to two Georgia Tech computer scientists. Anirudh Ramachandran and
Nick Feamster sorted through 10 million spam messages intercepted by an Internet "spam sinkhole," and analyzed their routing information, IP addresses and other electronic fingerprints. They conclude that spam filters searching through message contents are inferior to potential network-level protections. "Amber-Lynn" would not have reached Philoneist's Hotmail account if Internet service providers collaborated to build spam defenses into the Internet's routing system.