Spam is a growing problem for everyone with an e-mailbox. The proliferation of unsolicited offers for pornography of all kinds, Viagra at wholesale prices, and pills that enhance the size of your sex organs are clogging up the Internet faster than you can say bandwidth.

Microsoft, the largest software company in the world and operator of the worldwide MSN network, is also one of the largest victims of spammers, That why the Redmond-based giant is using Washington State’s tough anti-spam law to prosecute suspects around the world.

Every piece of spam includes one or two pieces of real information. It may be a phone number, a Web site address, or a company name, but somewhere, somehow, there are clues. Those clues helped Microsoft trace e-mails across 34 countries, identify the senders, and file lawsuits against 15 people and businesses accused of sending more than 2 billion deceptive e-mails that flooded customers’ in boxes and Microsoft’s computer systems.

Microsoft announced the 15 lawsuits, filed in Washington state and the United Kingdom against defendants who allegedly sent junk e-mails offering everything from body enhancements to pornographic photos. In all but the two U.K. cases, Microsoft is suing the defendants under Washington state’s anti-spam law, considered one of the toughest in the country. The company is seeking court orders to stop the spammers and requests unspecified monetary damages.

Twelve of the lawsuits were filed in King County Superior Court. One was filed in U.S. District Court for the Central District of California in Los Angeles, where the defendant lives. Two others, which cite violations of U.K. privacy laws, were filed in London’s Royal Courts of Justice.

The 15 lawsuits address some of the most misleading, deceptive, and offensive spam e-mail received by Microsoft customers, and Microsoft says it may file additional suits.

According to the software giant, the defendants sent out unsolicited e-mails with deceptive subject lines and bogus addresses. The e-mails advertised everything from adult Web sites to dating services, including a compact disc detailing how to become a high-volume spammer. Some also violated trademark laws, Microsoft said, by pretending to be e-mail from Microsoft advising recipients that a virus had been detected on their computer and they go to the defendant’s Web site.

Washington state’s anti-spam law bans bulk or commercial e-mail with misleading information in the subject line, invalid reply addresses or disguised paths of transmission. It allows for damages of at least $500 per message for individuals and $1,000 for Internet service providers.

Ironically, earlier this year Microsoft sought to weaken provisions of the law by capping the amount that could be awarded to $25,000 a day, but the bill died.