A common Internet fraud using e-mails forged to look like those of legitimate retailers is coming under serious legal pressure from Amazon.com and others.

The practice of concealing the true sender of an e-mail by making it appear to come from a different sender is called e-mail "spoofing." Spoofing is a widespread problem for companies with well-known domain names that communicate with customers through e-mail marketing tools such as Web-based newsletters and advertisements.

The problem of spoofing is not just another bothersome form of spam-it's consumer fraud, and Amazon is encouraging customers to report suspected spoofing by sending e-mail to a special account in hopes of catching the culprits and taking them to court.