The head of a Seattle-based e-mail marketing firm that sent millions of spam messages with fake headers was sentenced to four years in jail this week for mail fraud, among other charges.

Robert Soloway, the CEO of Newport Internet Marketing Corp. who federal investigators dubbed the "Spam King," pleaded guilty in March to a series of charges stemming from so-called broadcast e-mail services that used false opt-in addresses or forged headers to promote the company's own Website.

"Because these victims could sometimes be specifically identified based on their unique e-mail addresses or domain names, they were sometimes mistakenly blamed for the spamming activity," prosecutors said in Soloway's indictment.

To avoid detection, Soloway constantly moved the Website, which has been hosted on as many as 50 domains since 2003.

After promising a full refund to customers who weren't satisfied with the company's services, Soloway instead threatened those that complained with additional charges, referring them to a collection agency.

In a plea agreement, Soloway also disclosed that he failed to file an income tax return on over $300,000 in gross revenue from 2005.

In addition to jail time, Soloway was also ordered to perform 200 hours of community service.