The Federal Trade Commission (FTC) has claimed a small victory in the battle against spam email messages.

"Spam has not, as once feared, destroyed the promise of email," the FTC said in a report evaluating the effectiveness of the US Can-Spam Act.

The Controlling the Assault of Non-Solicited Pornography and Marketing Act was adopted in 2003. The law prohibits emails with a forged 'from' address, and requires marketing emails to offer recipients a way to unsubscribe.

But the legislation has been criticised for lacking teeth, as it has failed to do anything about spam sent from abroad.

The FTC report, however, claimed that the Can-Spam Act has been effective in two areas. It has forced some legitimate companies that used to send spam to become more consumer friendly marketers, and has provided ISPs and authorities with a weapon against spammers.

"More than 50 cases brought by the FTC, the Department of Justice, state attorneys general and ISPs demonstrate Can-Spam's enforcement efficacy," the report boasted.

Andrew Lockhart, director of product marketing at email security vendor Postini, agreed with the FTC's assertions.

"While Can-Spam is clearly insufficient if its goal is to stop spam, it is good to have it on the book," he said.

"If you can find a guy that sends spam, we can prosecute them. But there is no change that helps find the bad guys, not without fundamentally changing internet protocols."