Microsoft has made its boldest move to date in the war against spam by issuing fifteen legal complaints against alleged e-mail spammers in the United States and the United Kingdom.

In an announcement released on June 17, Microsoft accuses the fifteen defendants of collectively sending over 2 billion deceptive, unsolicited e-mail messages to its customers. The lawsuits are targeted at stopping some of the most offensive e-mail practices affecting Microsoft customers. In some cases, defendants are alleged to have used deceptive and misleading subject lines to disguise e-mail messages that actually contained pornographic images, dating service solicitations and other adult services.

"We are expanding very substantially our global effort to fight spam," said Microsoft General Counsel Brad Smith in an interview. "This is something we are dedicating more and more resources to."

The sending of deceptive, offensive and unsolicited e-mails - commonly referred to as "spamming" - has become the number one complaint among Internet users. Last month, MessageLabs, a leading provider of Internet security systems, indicated that spam now accounts for more than 50% of business e-mail. Their study further shows that the accounting profession is especially vulnerable to deceptive, misleading e-mail "spam." Another study released by Ferris Research in January estimated that spam costs American businesses approximately $9 billion a year.

Microsoft is taking advantage of a pro-consumer law in Washington that allows for criminal prosecution of someone who sends commercial e-mail with a false or misleading subject line, or "hijacking" a third party's domain name without their permission.

Microsoft, Yahoo! Inc., Earthlink and America Online continue to work together to help combat the technical issues involved in curbing spam.