Microsoft, together with AOL, Earthlink and Yahoo, have embarked on another set of anti-spam lawsuits.

New cases have been taken out in Virginia, Georgia, California and Washington accusing people of violating the federal CAN-SPAM Act, along with other state and federal laws.

It is the second time that the ISPs, united in the Anti-Spam Alliance, have taken legal action against spammers. In March, they sued more than 220 alleged spammers responsible for sending out hundreds of millions of pieces of unsolicited e-mail.

Microsoft on its own also started suing more spammers in September, following a successful $4 million verdict from an earlier case.

In the new round of lawsuits, AOL is suing numerous defendants and seeks damages as well as court orders forcing the spammers to give up profits and cease their activities. One suit targets spam sent via instant messaging - the first such lawsuit, according to AOL.

AOL and EarthLink are focussing on spammers hawking controlled substances, including Vicodin and other prescription drugs. EarthLink's lawsuit also charges numerous unnamed defendants with sending spam advertising mortgages and loans.

Microsoft is charging one named and two unnamed defendants with sending millions of e-mails advertising herbal growth supplements, mortgage services and get-rich-quick schemes. The defendants spoofed the origin of their e-mail messages to show it came from Microsoft, AOL, EarthLink or Yahoo accounts, the lawsuits say.

Yahoo filed suit against East Coast Exotics Entertainment and Epoth, saying the companies disguised their identity and sent sexually-explicit messages designed to circumvent spam filters.

By suing top spam senders, the Anti-Spam Alliance members hope to make the spam business less attractive. Although many spammers are unknown, the group has said in the past that they plan to use the law enforcement tools available under CAN-SPAM to identify the unnamed defendants, and shut them down.