Microsoft has filed two lawsuits over the past weeks, looking to crack down on spam on its Windows Live Hotmail network.

The "John Doe" lawsuits were filed against unknown alleged spammers who had been sending large quantities of spam advertising debt relief and adult Web sites to Hotmail accounts.

Microsoft alleges that a company doing business under the name Consumer Solutions Network sent "misleading, deceptive, and unsolicited commercial e-mails advertising debt relief help to Windows Live Hotmail account holders."

The spam contained subject lines such as "Michelle, accounts over the limit," or "Robert, Payment not received," the suit alleges.

Consumer Solutions Network, which could not be reached for comment on this story, operates several Internet domains including myfinancialsolutions.org, consumersolution.org, and financialsolutionsonline.org, according to Microsoft.

Microsoft has also sued unnamed defendants for sending spam that promoted pornographic Web sites through Hotmail. Microsoft claims that these spammers not only flooded Hotmail accounts with unwanted messages, but also used Hotmail itself to send large volumes of spam. "Many of defendants' illegal e-mail messages were sent using... accounts obtained through false or fraudulent pretenses," Microsoft claims.

Companies like Microsoft, AOL and Earthlink have launched a large number of these lawsuits in recent years, said Venkat Balasubramani, the principal of Balasubramani Law, and author of the Spam Notes blog. "They serve a deterrent purpose and they also can be a mechanism for investigation. You can issue subpoenas and dig around a little bit to find what's going on," he said.

Microsoft has filed such lawsuits on an almost-monthly basis over the past year, he added.

In April and May of this year it filed similar lawsuits against several alleged stock scammers.

These latest lawsuits were filed in King County Superior Court in Seattle. The Consumer Solutions Network lawsuit was filed on June 13. The suit relating to pornographic spam was filed on Tuesday of this week.