Spam comes under attack in British courts (Advanced)

Microsoft has taken the unprecedented step of launching two legal actions in Britain against distributors of unsolicited junk email as part of a global attempt to halt the spam epidemic.

The software company announced yesterday that in addition to 15 lawsuits it has filed in the United States, it was bringing two cases against alleged spammers in this country under the Computer Misuse Act - Microsoft's first attempt to use the courts to battle spam in Europe.

Jean-Philippe Courtois, president of Microsoft Europe, said: "Spam is one of the most serious problems facing customers today and we have a responsibility as an industry leader to help people address the issue and restore confidence and utility in email."

Both cases involve so-called dictionary attacks on the company's servers, in which the spammer attaches random email prefixes to a known domain name, for example joebloggs@msn.com. This tactic allows the spammer to generate lists of "live" email addresses which can be sold on or used for subsequent spam attacks.

In the first case, Microsoft's servers were attacked more than 455,000 times, automatically generating more than 3m email addresses, of which more than 225,000 were valid.

The second case involved an attack on both Microsoft and a British anti-spam organisation. Every invalid address generated sent an undelivered message to the anti-spam group in an attack so severe that its email system was disabled for several days.

The crackdown comes amid growing fears over the threat that the explosion in spam poses to the viability of the global email system. Unsolicited junk mail, most of it distributed by 150 people based in the US, accounts for about half of all email traffic, much of it offering hardcore and illegal pornography and get-rich-quick schemes.

Recent research estimated that spam cost European businesses about £2.5bn last year, and it continues to proliferate at an exponential rate.

Microsoft has a vested interest in leading the battle against the spammers. Its free webmail service, Hotmail, is one of the worst affected by junk mail and it is the company's Windows PCs that are most vulnerable to attack by spammers seeking to hijack computers to distribute the mail.