Affiliate marketing is a leading source of spam, experts say; many companies do not scrutinize their online partners

• The biggest annoyance on the internet is not the guy trying to sell you a knockoff watch or prescription painkillers, it's the marketing scheme that rewards spammers who drive customers to his site.
• Affiliate marketing, a system in which a business pays a commission to those who drive paying purchasers to its website, is responsible for much of the spam that clogs inboxes, search results contaminated with useless pages selling ring tones, and a never-ending barrage of pings and fake TrackBacks that have driven many bloggers to shut down comments on their sites.
• Match.com, an online dating service, uses carefully chosen affiliates to reach niche audiences, such as mountain climbers or ethnic groups, according to spokeswoman Kristen Kelly.
• The site prevents abuse of the program by prohibiting its affiliates from marketing by e-mail and by giving itself wide leeway in deciding when to cut ties with an affiliate.
• Not all programs police their affiliates so closely, though recent antispam lawsuits and enforcement actions may inspire companies that take a wink-and-nudge approach to affiliates to take a closer look.
• The CAN-SPAM Act of 2003 makes a company liable for junk e-mail sent on its behalf if it should have known of the spam or it took no reasonable action to police its affiliates.
• CAN-SPAM gives the federal government, states and ISPs wide powers to sue companies who hire spammers, because the bill defines the senders of an e-mail to include anyone who procured the services of a spammer, according to Steven Wernikoff, a Chicago-based staff attorney for the FTC.
• "The judge said, 'If you are procuring the sending of e-mail or profiting from the sending of e-mail, you are potentially liable if your affiliate sends e-mail that violates the law.'"