The US suits are filed against alleged spammers that try to fool customers by providing false information in the "from" line of the e-mail or using deceptive subject lines, such as "Your Visa bill" or "Credit Card Refund" to trick them into opening the message.
Tim Cranton, a lawyer at Microsoft, explained: "We're focusing our efforts on the type of spam that troubles our customers the most: consumer deception and unsolicited pornography."
Cranton cites a finding by the FTC that 66% of spam has some type of false information, adding that such e-mail often comes "in the form of get-rich-quick schemes, adult services or purported health offerings."
The US lawsuits rely upon an anti-spam statute in Microsoft's home state of Washington. The two British actions are seeking to rely on the Computer Misuse Act of 1990. It is likely to be the first action in the UK to use this anti-hacking statute to fight the problems of spam.
Microsoft is also lobbying for federal law in the US – and in countries worldwide – to crackdown on spam. Cranton says that when Microsoft encounters spam activity around serious criminal issues, such as child pornography, consumer fraud or identity theft, the company immediately notifies appropriate government agencies.