Escalating its fight against unwanted spam e-mail,\u00a0Microsoft\u00a0Tuesday announced that it has filed 15 civil lawsuits -- 13 in the U.S. and two in the U.K. -- against alleged spammers targeting the company's customers.The U.S. lawsuits allege that the defendants are responsible for flooding Microsoft's customers with more than 2 billion deceptive, unsolicited e-mail messages, according to Brad Smith, senior vice president and Microsoft's general counsel. He spoke at a news conference held by the company this afternoon to explain its latest antispam actions."Spam is a growing problem and it's a global problem, and it requires a global solution," Smith said. "We at Microsoft are ramping up our efforts to combat spam around the world."Smith said spam must be addressed through a variety of ways, including improved technology; more collaboration among companies, like the new\u00a0antispam partnership\u00a0formed by Microsoft, EarthLink, AOL and Yahoo; and better collaboration between Internet companies and government.Smith also said Microsoft believes that stronger legislation is needed to combat spam, as long as any new measures don't stifle the opportunity for new business.Microsoft said the lawsuits filed Tuesday are targeted at stopping some of the most offensive e-mail practices affecting the company's customers. It filed its legal actions under Washington state's antispam law, which provides ISPs with the tools they can use to take action against spammers. The cases address some of the most misleading, deceptive and offensive spam e-mail received by Microsoft customers, the company said.Some defendants are alleged to have used misleading subject lines to disguise e-mail messages containing pornography and other adult services. One case involves e-mail messages that include a false virus warning. And in other cases, Microsoft alleges, defendants "spoofed" a senders' e-mail addresses, misleading recipients by making it appear that an e-mail message originated from Hotmail.com or other another familiar e-mail account.According to Microsoft, some of the defendants are listed as known spammers on Internet registries that track spam activities worldwide.The company also touted its own efforts to implement more effective antispam technology features in its products, including MSN 8 and the upcoming release of Microsoft Exchange and the Outlook messaging and collaboration software in Office 2003. Microsoft also said it is continuing to bolster filtering capabilities to make it easier for computer users to distinguish wanted e-mail from spam by providing more-reliable input to filtering technologies and developing ways to verify whether the senders of messages are who they say they are.