Hoping to turn the tide on spam zombies, Microsoft has filed suit against entities it said used compromised PCs to send millions of junk e-mail messages.

The company has identified 13 different spamming operations that use such "zombies," it said Thursday. A lawsuit was filed against unnamed defendants in August. Since then Microsoft has tracked down some of the people behind the operations, said Tim Cranton, director of Internet Safety Enforcement Programs at Microsoft in Redmond, Wash.

"We have identified a number of entities in North America that we feel the evidence will show are liable and culpable for the spamming that occurred," Cranton said.

Read more about Microsoft's spam zombies hunt at http://news.zdnet.com/2100-1009_22-5917817.html.