Days after anti-spam laws came into force in the UK, US President George Bush has signed a bill that establishes rules for commercial email and penalties for sending unsolicited mass spam emails in the States.

Known as the CAN-SPAM Act, the Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003 will take effect on January 1. The law prohibits the use of false header information in bulk commercial emails and requires unsolicited messages to include opt-out instructions. Penalties for violations include fines of up to $250 per email, capped at up to $6 million.

The bill's authors, Montana Republican Senator Conrad Burns and Oregon Democrat Senator Ron Wyden, praised the legislation as a powerful tool for countering the spam onslaught cluttering inboxes.

"Swift and aggressive enforcement will be essential, and Senator Burns and I will continue to push the Federal Trade Commission and others to use the tools this law gives them to fight against spam," Wyden said in a written statement.

Several major ISPs (Internet service providers) and e-commerce companies lined up to endorse the legislation. America Online hailed the CAN-SPAM Act's passage as a "watershed event" that will help defeat spammers relying on fraud and evasion, while eBay called the enactment "great news." Yahoo said the legislation is "a victory for consumers and the Internet" and will provide important new legal weapons for businesses fighting spam.

Critics of the bill, however, argue that its effects will be mostly ceremonial. Bulk email operators outside the US will be beyond the law's jurisdiction, and the act overrides state antispam laws that are in some areas stronger than the new federal regulations.

The new law is unlikely to change spammers' behavior, research firm Gartner Inc. said in an advisory. The research firm still expects filtering technologies and e-mail management policies to be the best way for businesses to fend off unwanted messages. IDC estimated in a recent study that spam constitutes 32 percent of the e-mail volume sent daily in North America, up from 17 per cent two years ago.