SPAM

SPAM is unwanted e-mail. Anyone who has an e-mail account has received SPAM. Usually it takes the form of a marketing solicitation from some company trying to sell something we don't want or need. To most of us it is just an annoyance, but to a server it can also be used as a denial-of-service attack. By inundating a targeted system with thousands of e-mail messages, SPAM can eat available network bandwidth, overload CPUs, cause log files to grow very large, and consume all available disk space on a system. Ultimately, it can cause a system to crash.

SPAM can be used as a means to launch an indirect attack on a third party. SPAM messages can contain a falsified return address, which may be the legitimate address of some innocent unsuspecting person. As a result, an innocent person, whose address was used as the return address, may be spammed by all the individuals targeted in the original SPAM.

E-mail filtering can prevent much unwanted e-mail from getting through. Unfortunately, it frequently filters out legitimate e-mail as well.