In addition, the free e-mail accounts that have sprung up on the Internet in recent years benefit spammers and legitimate users alike. This makes it particularly difficult to close down spamming operations, says Joyce Graff, vice president and research director of e-mail at the Gartner Group . She likens the situation to con men. They set up shop in a fake storefront, and by the time the police arrive, they're gone. A server that allows third-party mail transfer is known as an open relay.
Spammers use software to scan large swaths of the Internet for open relays.
Traditional defenses against spam, such as installing enterprise mail filters and reporting spammers to ISPs, have their limitations. While mail filters can eliminate some spam, you may still incur the processing costs. As for the ISPs, most major service providers actively boot spammers from their services if they receive complaints. However, as mentioned earlier, it's easy for a spammer to find another service provider. In addition, many hosting companies tolerate spamming activity.