The CAN-SPAM bill, sponsored by Senators Conrad Burns (R-Montana) and Ron Wyden (D-Oregon) has been approved by the Senate, and has gone before the House of Representatives for the approval of some minor technical changes, before being signed into law by President Bush.

The legislation prohibits the use of a false return address or misleading subject line on commercial e-mails, stipulates that consumers must be provided with a valid way in which to opt out of mailing lists, and requires that the sender's physical address must be contained in the e-mail.

There must additionally be a clear indication that the e-mail contains advertising material.

However, Gartner believes that there are loopholes in the proposed law which unscrupulous spammers will find it easy to exploit. For example, although the bill authorises the Federal Trade Commission (FTC) to establish a 'Do Not Spam' registry, Gartner argues that it is not made clear which agency will be responsible for implementing internet users' requests.

The research firm also suggested that ISPs and those offering e-mail filtering services will have to develop new techniques to differentiate between legitimate advertising material and spam, both of which will be obliged to carry an 'ADV' tag in the subject line.

Finally, Gartner suggested that spammers may simply opt to ignore the legislation, or leave the country in a virtual sense, by using offshore ISPs to send spam. This would effectively put them beyond the reach of US law.