The Federal Trade Commission has asked a U.S. District court judge to block an allegedly illegal spam operation that uses deceptively bland subject lines, false return addresses, and empty "reply-to" links to expose unsuspecting consumers, including children, to sexually explicit material.

The agency alleges that Brian Westby of Ballwin, Mo., used the spam in an attempt to drive business to an adult Web site, "Married But Lonely." The FTC has asked the court to order a halt to the deceptive spam, pending trial. It will seek a permanent injunction at trial.

According to the FTC complaint, the defendant sent spam with subject lines that would disguise the contents of the e-mail. For example, subject lines have included "Did you hear the news?" and "New movie info." When consumers opened the e-mail messages, they were immediately subjected to sexually explicit solicitations to visit the defendant's adult-oriented Web sites. Because of the deceptive subject lines, consumers had no reason to expect to see such material, the FTC alleges.

In some cases, consumers may have opened the e-mails in their offices, in violation of company policies. In other cases, children may have been exposed to inappropriate adult-oriented material, the FTC complaint notes. The defendant's spam provides a hyperlink or an e-mail address for consumers who wish to "unsubscribe"or stop receiving e-mail in the future. According to the FTC, when consumers used the hyperlink or e-mail address in an attempt to get off the mailing list, they received an error message - they could not unsubscribe.

The FTC also alleges that the defendant used false "reply to" or "from" information in the e-mail, making it appear that some innocent third party was the sender. This practice is known as "spoofing." As a result, thousands of undeliverable e-mails flooded back to the computer systems of these third parties, deluging their computer systems with an influx of spam that couldn't be delivered to the addressee. In addition, it unfairly portrayed these innocent bystanders as duplicitous spammers, often resulting in their receiving hundreds of angry e-mails from those that had been spammed, according to the FTC.

In papers filed with the court, the agency says the deceptive practices violate the FTC Act. The complaint says the defendant and his businesses have and will continue to injure consumers, and that the defendant has been unjustly enriched as the result of his illegal scheme. The agency has asked the court to halt the scheme.