The first person to be prosecuted under tough US federal anti-spam laws has pleased guilty to the charges.
Daniel Lin has admitted his guilt on three charges brought by federal prosecutors, who are using anti-spam laws brought into use in 2004.
Two of the charges relate to the sending of millions of unsolicited spam e-mails, and a third charge is for a firearms violation offence.
Lin, 30, from Michigan, faces a five-year prison sentence and a $250,000 (£147,000) fine, according to federal officials.
Lin is said to have worked with three other men in sending out more than 450,000 spam advertisements, pushing fraudulent weight-loss and erectile dysfunction products.
Lin is expected to be sentenced in May. In a private prosecution brought by a small US ISP recently, a Florida man was fined around $11bn in a district court for sending out millions of spam messages, but the ISP doesn’t expect to be able to enforce the award.
The federal laws being used in the Lin case are expected to lead to jail sentences for perpetrators.