The term is said to derive from a famous Monty Python sketch ("Well, we have Spam, tomato & Spam, egg & Spam, Egg, bacon & Spam...") that was current when spam first began arriving on the Internet. SPAM is a trademarked Hormel meat product that was well-known in the U.S. Armed Forces during World War II.
SPAM, the original tinned meat product has been around since the 1930's. I think the name is an abbreviation of Spiced Ham. The use of the term spam to indicate unsolicited commercial emails is explained here. http://www.spam.com/ci/ci_in.htm.
PS: I used to eat SPAM as a kid. Fry up a slice of SPAM and make a SPAMwich, YUM!!!!!
SPAM is yummy, yeah I made an account here then ran off to devever.net for awhile. Enfusion nothing is sacred when I'm around. As for ekzibit aka concise dictionary of banana's, nice work digging up all that crap back there. Knowledge is power unless one has a pack of explosives attached to one back.