Chapter 12. How Email Spam Works

One of the most contentious issues to surface on the Internet in the last few years has to do with what Internet users call spam. Spam is unsolicited junk email that commercial companies send out, asking you to buy their goods and services. At times it might contain inducements to visit the seller's site. The email usually contains a phone number to call, an address to send money to, or a website to visit to buy the goods and services. Increasingly, spam also contains pornographic content and scams.

The term spam comes from a Monty Python skit in which every item on a menu contained Spam luncheon meat. It was originally used to refer to unsolicited postings for commercial products or services on Usenet, especially when they were cross-posted to several newsgroups.

Spam might seem like a minor annoyance, but the truth is that it can cause major problems. Spam floods the Internet with unwanted mail, which can lead to delayed or lost mail. It clogs the Internet pipeline, making other information slower to send. It wastes time for those who have to go through their email boxes deleting unsolicited mail, especially when they pay for their email service by the hour. Additionally, it's fairly common for spammers to hide their real email addresses by forging other people's names onto the From or Sender header of an email message. So, those people whose names were forged might be the target of angry mail. This makes it difficult for webmasters and mail administrators to filter spam messages by From address or domain name. Sometimes spammers even use other people's servers to deliver their bulk email; in essence, forcing someone else to pay the costs of the spammer's mail delivery.

Spam has other dangers as well. Spam is often used to scam unsuspecting victims, for example by sending out false emails claiming someone needs to log in to their bank, and then sending the person to a spoofed bank site. The spammer then steals financial information. This technique, called phishing, is covered in Chapter 49, "The Dangers of Spyware and Phishing."

In some ways, spam is not very different from traditional junk mail. Spammers buy or compile massive lists of email addresses, in the same way that junk mailers buy or compile U.S. postal addresses. The spammer then uses special software to send a solicitation to every person on the listnot uncommonly, tens of thousands of pieces of email in a single spam mailing. To hide their true identities, spammers forge names onto the headers of email messages and even "relay" their spam to another mail server on the Internet, so that finding out where the mail comes from is impossible. Often, a user will request to be taken off the list by replying to email addresses the spammers provide. However, this verifies the user's address and he will get even more spam.

A variety of ways have been devised to block spam, including having email filters on email software ignore any mail from known spammers. The software also examines the content of email messages to try and determine whether it is spam. In addition, several states have passed anti-spam legislation, and Congress has also passed a federal law called the Can Spam Act. But the laws are not particularly effective, and the best way to protect yourself is to install anti-spam software.