Spammers have developed a complex arsenal of techniques for spamming. Important spamming techniques are described in the following sections.
An open relay is a computer that allows any user to send email. Spammers use such computers to send spam without the email being traced to its true origin. Open relays are discussed in detail in Chapter 3.
Early spammers had to collect email addresses in order to send spam. They use a variety of methods, from collecting email addresses from the Internet and Internet newsgroups to simply guessing email addresses. Email address collection is discussed in detail in Chapter 4.
Most people can detect spam from the email subject or sender. It is often easy to discard spam emails without even looking at the body. One technique used by spammers is to hide the true content of their emails. Often, the subject of an email is a simple "Hi"; alternatively, an email might appear to...