Two men in Los Angeles have been jailed for two years after they sent 50 million e-mails as part of a scam which almost brought the largest internet providers to a standstill.
Steve Shklovskiy and Yan Shtok, both 23, have also been ordered to pay £69,000 compensation for their role in the September 1999 scheme.
The men pleaded guilty to fraud charges in December 1999. Two others were sentenced to probation in July.
Authorities said Shklovskiy and Shtok devised a way to use personal computers equipped with commercially available software to "harvest" electronic mail addresses.
They then sent a mass e-mailing, asking recipients for a £24 "processing fee" in exchange for a chance to work at home stuffing envelopes.
More than 12,000 people were duped. Internet providers, including AOL, AT&T and Mindspring, were besieged by customer complaints and their systems were threatened by the overload.
The plea agreements require the men to reveal to the internet providers how they accomplished their scheme.