They sent billions of emails directing recipients to websites advertising bogus male enhancement drugs and weight loss pills shipped from India, which they falsely claimed had come from a licensed pharmacy in the US.
Atkinson and Smith allegedly controlled a "botnet" of 35,000 computers, capable of sending 10 billion email messages a day.
Servers in China hosted the websites and the drugs were shipped from India, while operatives in Cyprus and the former Soviet republic of Georgia processed credit card information.
Three million complaints were lodged against the spammers in a six-month period against Atkinson's Australian-registered company, Inet Ventures, which was one of four companies peddling prescription drugs targeted by the FTC.