The lawsuits, filed in Washington State Superior Court in King County, allege that the defendants violated Can-Spam's "brown paper wrapper" requirement, which calls for labeling sexually oriented content as "Sexually-Explicit" in the e-mail subject header and in areas where the e-mail can be initially viewed.
"Sexually explicit materials and publications for sale in stores are required by law to be covered from view with a brown paper wrapper, and it's important that consumers are protected online in the same way," Nancy Anderson, Microsoft deputy general counsel, said in a statement.
The lawsuits also allege that the defendants, who have yet to be named, violated Washington state laws and provisions ofthat prohibit the use of --computers being controlled without the PC owners' knowledge--to route spam e-mail messages. Microsoft's suits also allege that the defendants failed to offer unsubscribe options and working return addresses.
Last month, Microsoft filed a lawsuit against a spammer who was allegedly promoting sexually explicit Korean-language Web sites. In all, the software giant has taken more than 100 legal actions against alleged spammers worldwide.
Microsoft and a number of other Internet companies have been aggressively pursuing spammers. Microsoft, America Online, Yahoo and EarthLink, which together make up the Anti-Spam Alliance,in October against people who allegedly violated the Can-Spam Act.
The Anti-Spam Alliance also took, in the industry's first major round of lawsuits against alleged spammers under the Can-Spam Act. The law took effect Jan. 1.