US software giant Microsoft has won a $7m (£3.9m) court settlement from a businessman considered to be one of the world's biggest senders of spam e-mail.
Millions of spam messages clog up email boxes every year
Scott Richter agreed to pay the sum after Microsoft filed a lawsuit against his internet firm Opt In Real Big.
Microsoft alleged Opt In Real Big had sent millions of unsolicited commercial e-mails, using forged sender names and false subject lines.
Mr Richter denied any wrongdoing, but said his firm's operations had changed.
Microsoft had estimated that Mr Richter's business was sending 38 million spam messages a year.
The software giant said the court settlement was a major step in its battle against spam e-mails, which are notorious for clogging up e-mail inboxes.
As a result of joint lawsuits filed in 2003 by Microsoft and New York State attorney general Eliot Spitzer, Mr Richter pledged he would now only send spam e-mails to people who had confirmed they were willing to receive them.
"We have now proven that we can take one of the most profitable spammers in the world and separate him from his money," said Microsoft chief counsel Brad Smith.
"I think that sends a powerful message to other people who might be tempted to engage in illegal spam."
Opt In Real Big describes itself as the US's "fastest growing online marketing company."
In a statement released through Microsoft, Mr Richter said: "In response to Microsoft's and the New York attorney general's lawsuits, we made significant changes to OptInRealBig.com's emailing practices and have paid a heavy price."
He added: "I am committed to sending e-mail only to those who have requested it and to complying fully with all federal and state anti-spam laws."
Microsoft said it planned to use the money from Mr Richter and Opt In Real Big to further boost its campaign against e-mail spammers.