"Spam King" Robert Alan Soloway, who owns Newport Internet Marketing Corporation, pleaded guilty on Friday in Seattle's U.S. District Court to mail and e-mail fraud and willful failure to file a tax return.

Soloway could receive up to 20 years in prison and over half a million dollars in fines when he is sentenced on June 20 by U.S. District Judge Marsha J. Pechman. The bulk of Soloway's sentence is likely to come from the mail fraud offense, which is punishable by up to 20 years in prison. E-mail fraud is punishable by up to 5 years in prison. Willful failure to file a tax return is punishable by up to a year in prison.

Assistant United States Attorney Kathryn Warma said she hopes that Soloway's fate will deter further spamming. "We've only just begun," she said. "Spamming is of high interest to the federal law enforcement community and we're going to be doing more cases. Hopefully, they're going to get the message now."

U.S. investigators have referred to Soloway as "the Spam King," though that title has also been bestowed on the likes of Scott Richter, Alan Ralsky, and Sanford Wallace. The current "spam king," or perhaps spam czar, is Russia's Leo Kuvayev, according to Spamhaus.org.

Warma said that U.S. authorities are working with officials in other countries to spur prosecution of spammers outside U.S. jurisdiction.

Between November 2003 and May 2007, according to the government, Soloway and his company sent tens of millions of spam messages in support of his company's Web sites, products, and services. The messages contained false and misleading header information, and were relayed through bot nets -- networks of PCs compromised as a result of infectious malware.

Newport Internet Marketing Corporation (NIMC) sold "broadcast e-mail services." The company promised permission-based marketing but delivered spam. This resulted in the blacklisting of some of the company's clients.

In 2005, Microsoft won a $7.8 million civil judgment against Soloway for spamming through its Hotmail service. That same year, Oklahoma businessman Robert Braver won a $10 million civil judgment and an injunction against further spamming in his lawsuit against Soloway.

In 2005, Soloway mocked Microsoft's ability to collect any judgment against him, according to a note posted on the Spamhaus.org Web site that's purportedly written by Soloway. "It doesn't matter if they receive a judgment for $8 million or $8 billion, Microsoft won't see a single dime, (or penny) as all my assets are protected under the Washington State Asset Protection Act," the message says.

Warma said Soloway's defiance of the Oklahoma court order against further spamming will probably influence his sentence. Violation of a court order adds two points under federal sentencing guidelines, she said, which might add 18 months to Soloway's sentence.