Robert Soloway faces 35 federal charges, including mail fraud, wire fraud, fraud in connection with electronic mail, aggravated identity theft and money laundering. He was ordered held until a bail hearing on Monday.

Prosecutors said he used networks of compromised computers to send fraudulent mail to tens of millions of people.

Soloway is accused of sending unwanted e-mail messages directing recipients to the Web site for his company, Newport Internet Marketing Corporation, which made a number of false and fraudulent claims about the products and services, authorities said.

"Spam is a scourge of the Internet, and Robert Soloway is one of its most prolific practitioners," said Jeffrey C. Sullivan, U.S. attorney for the Western District of Washington. "Our investigators dubbed him the 'Spam King' because he is responsible for millions of spam e-mails."

Federal authorities said he also sold the information to others about how to send spam.

Microsoft officials said Soloway is one of the world's top 10 spammers.

Microsoft sued Soloway in 2003 and won a $7.8 million verdict, but they said he did not pay.