Spam

From ASSPSMTP

spam is "bad" or unwanted e-mail, and is considered the opposite of ham.

The word spam should not be capitalized when referring to e-mail, as the capitalized version is a registered trademark of the SPAM luncheon meat made by Hormel. The diametric use of ham and spam are (generally-speaking) a reference to the combination and cultural adaptation of two historical events:

1. The British food rationing during World War II; where ham was rationed for the war effort, but SPAM luncheon meat (something people became tired of having as a forced substitute) was not.
2. The repetitive nature of being "spammed"; in what is considered to be the first dramatization of such event in an infamous sketch parodying the British food rationing with SPAM luncheon meat on Monty Python's Flying Circus as originally televised on The BBC, December 15, 1970 - almost 10 years before message "spam" would first appear in on-line chat rooms or the wide-spread public use of Internet e-mail.

For more information see the spam Wikipedia article.