A US software developer has pleaded guilty to charges related to creating and marketing software designed to send bulk commercial email messages.

David S. Patton, 49, of Centreville, Virginia, pleaded guilty to aiding and abetting violations of the CAN-SPAM Act committed by spam kingpin Alan Ralsky and Scott Bradley, both of West Bloomfield, Michigan, and other spammers, the DOJ said.

Under the terms of his plea agreement, Patton faces up to six years in prison, a fine of $3,000 (£1,800) and the forfeiture of $50,100 in proceeds for the sale of his software. Patton pleaded guilty in US District Court for the Eastern District of Michigan.

The CAN-SPAM Act, passed by the US Congress in 2003, prohibits sending commercial email messages with false sender information and with inaccurate subject lines. It requires the senders of unsolicited commercial email to provide working opt-out mechanisms and include their physical addresses in the email.

From January 2004 to September 2005, Patton and his company, Lightspeed Marketing, developed and sold customised software products that allowed users to send large volumes of spam email at high speeds and disguise the true origin of the emails from recipients in order to evade antispam filters, blacklisting and other spam-blocking techniques, the DOJ said.

Patton, in his plea agreement, acknowledged that he designed the Nexus software package to enable users to insert false information into the headers of the spam emails it sent, the DOJ said. Patton designed Proxy Scanner to enable users to make use of third-party proxy computers to relay or retransmit spam emails and disguise their true origin.

Patton sold both Nexus and Proxy Scanner to Ralsky and other customers, knowing that the two software programs would be used to commit violations of the CAN-SPAM Act, the DOJ said. Patton also provided ongoing support and product updates to his Nexus and Proxy Scanner customers with the intent to assist them in violating the CAN-SPAM Act, the agency said.

Patton is the 12th defendant charged in connection with the spam email operation run by Ralsky from January 2004 to September 2005. Ralsky, Bradley and six other defendants have pleaded guilty to CAN-SPAM-related charges and other offenses.

In June, Ralsky and four other people pleaded guilty to charges related to a stock fraud case involving spam messages that pumped up Chinese "penny" stocks. Ralsky faces up to seven years in prison on those charges, conspiracy to commit wire fraud and mail fraud and to violate the CAN-SPAM Act.