Microsoft has filed nine lawsuits against individuals and companies alleged to be involved in the distribution of spam.
The suits, all filed in the last month, include eight against individuals alleged to be behind spam campaigns that offered e-mail users a variety of products including generic online drugs, T-shirts, software, pornography and dating services.
The ninth lawsuit is against a web hosting company which catered to the spammer community by claiming to be "bulletproof", or incapable of being shut down.
The lawsuits are just the latest salvo in a legal war on spammers by Microsoft, as well as internet service providers such as America Online and EarthLink.
In June, Microsoft filed eight lawsuits against alleged spammers who used accounts at the company's Hotmail e-mail service and compromised PCs running its Windows software to send spam.
In the latest suits, Microsoft has also extended its reach to companies that sell services to spammers, according to the statement.
Microsoft filed suit against Levon Gillespie, who is described as a principal of "bulletproof" web hosting company cheapbphosting.com, as well as "various John Doe" defendants who use Gillespie's services.
According to text Microsoft said was taken from the cheapbphosting.com site, Gillespie "cater[s] for both established bulk e-mail experts and companies that have not used bulk e-mail before", using "China-based" servers "to ensure no problems arise from complaints generated by mail you send".
Microsoft claimed that spam that originated on servers on the cheapbphosting.com was routed through compromised computers in Korea, Japan, Israel and the UK, as well as Brazil, Germany, Switzerland, Canada and the US.
The e-mails contained forged or "spoofed" header information to make them look as if they came from Microsoft MSN and Hotmail accounts, the company said.
Microsoft said it has filed 70 lawsuits in the US, including the latest group, and is continuing to target spammers and those that support spamming.
Paul Roberts writes for IDG News Service