Ask any Internet user what they hate most about being online and you will usually hear an earful about spam. Spam is considered by many to be the scourge of the Internet. It is certainly a costly problem, both in time and in the costs organizations expend to fight it.

The first, and least common, is spammers that obtain temporary legal and real accounts with ISPs. This is less common because most ISPs quickly shut down these accounts. There are a few ISPs that turn a blind eye, but they are likely already known and blacklisted.

The second method used to send spam is through compromised hosts, usually workstations and home computers on high-speed connections such as DSL or cable modems. These systems are usually compromised and have become part of large networks of zombie systems called bot-nets.