Two men have been sent to jail for over five years each for their part in an international spam gang which bombarded innocent Internet users with sexually explicit images.

A federal judge sentenced Jeffrey A. Kilbride, of Venice, California, to six years in prison and his associate James R. Schaffer of Paradise Valley, Arizona, to five years and three months in jail. The two men were found guilty of charges including violating the CAN-SPAM act, conspiracy, money laundering, fraud and transportation of obscene materials. Kilbride received a higher sentence from US District Judge David G Campbell after the court ruled that he had tried to prevent a government witness from testifying at the trial.

Spam sent by Schaffer and Kilbride resulted in America Online receiving more than 600,000 complaints from users between 30 January and 9 June 2004. The spam messages were sent out to promote hardcore pornographic websites.

The two men used a variety of tricks to try and hide their whereabouts from the authorities. These included logging in remotely to servers based in Amsterdam to try and make their spam messages look like they originated from outside the USA, and using bank accounts in Mauritius and the Isle of Man.

"Spamming is a big money earner for cybercriminal gangs who have no qualms about swamping email inboxes with offensive messages or breaking into innocent people's PCs," said Graham Cluley, senior technology consultant for Sophos. "The authorities have sent a strong message to spammers that their activities will not be tolerated. If you send spam then you are running the gauntlet of spending years locked in a prison cell."

In addition to the jail sentences, each man received a fine of $100,000 and ordered to pay damages to AOL of $77,500. The authorities are also seizing over $1.13 million in revenues gathered by the criminal gang.

Other members of the gang, including work-at-home "mom" Jennifer Clason, Andrew Ellifson of Scottsdale, Arizona, and Kirk Rogers of Manhattan Beach, California, pleaded guilty to charges and turned state's evidence against Kilbride and Schaffer.