The Surprising Economics of E-Mail Spam

Every day three-quarters of all e-mail that flies across the Internet is spam. Some of it tricks customers into installing a virus or forking over personal information to use illicitly. But many spam messages are advertisements for companies that sell real goods, usually prescription drugs, knock-off watches, and pirated software. Millions of Americans see it as a way to save on drugs. “You pay the money, and you get a product,” says Stefan Savage, computer science professor at the University of California, San Diego.