Daniel J. Lin, 30, of West Bloomfield Township faces almost five years in prison and a fine of up to $250,000, the U.S. Attorney's Office in Detroit said.
Two of the counts are fraud charges involving millions of unsolicited spam e-mails. The other is possession of a firearm by a felon.
Lin is scheduled to be sentenced May 16 in U.S. District Court in Ann Arbor.
Lin and three other men were identified as participants in the spam scheme, which included multiple corporate identities, bank accounts and electronic storefronts used to send hundreds of thousands of e-mails for fraudulent weight-loss and erectile dysfunction products. Charges against the three other defendants were dismissed.