My research shows the term goes back to the late 1980s and the "MUD" community. A MUD is a multi-user-dungeon. That's a somewhat archaic term for a real time multi-person shared environment, which is to say a shared world where users can chat, move around and interact with locations and objects in the environment. MUDs were named that because the first reminded people of "adventure" or "Dungeons and Dragons" games that involved jointly exploring a cave or dungeon. Modern successors of the MUD include EverQuest and The Sims Online. But most people used MUDs to chat, and to play around and impress one another with objects they created. They were at first a highly evolved successor for the chat room. The term spamming got used to apply to a few different behaviours. One was to flood the computer with too much data to crash it. Another was to "spam the database" by having a program create a huge number of objects, rather then creating them by hand. And the term was sometimes used to mean simply flooding a chat session with a bunch of text inserted by a program (commonly called a "bot" today) or just by inserting a file instead of your own real time typing output. There are unconfirmed reports as well that the term migrated to MUDs from early "chat" systems. Rich Frueh believes the term originated on Bitnet's Relay, the early chat system that IRC was named after. When the ability to input a whole file to the chat system was implemented, people would annoy others by dumping the words to the Monty Python Spam Song. Peter da Silva reports use in early 80s chat on TRS-80 based BBSs, but feels since they imported other Bitnet Relay customs, the term may have come from there. Another unconfirmed report from a BBS user claims to have seen it defined as a "Single Post to All Messagebases" though this origin seems unlikely in my personal opinion. Another report describes indirectly a person simply typing "spam, spam..." in a MUD with a keyboard macro until being thrown off around 1985. My research has not found BBSers or Relay chatters using the term in USENET messages, so for now I conclude it was MUDders who brought the term to USENET and email. http://tinyurl.com/yrrzj

Apparently the terminology derives from the Monty Python SPAM sketch where everything in the menu contains spam as well as several people singing 'spam' in the background. This was seen as 'SPAMming' the dialogue. In early chat rooms and message boards some obnoxious users flooded the screens with 'SPAM SPAM SPAM' repeated over and over again in reference to the sketch. After this began to spread and other forms of this occurred 'spamming' became known as a term meaning "excessive multiple posting". Originally some businesses flooded newsgroups such as Usenet with adverts for their products and this gradually moved on to email which was seen as a more effective method. Still, the term 'SPAM' transferred with the different electronic medium and remains in use today. http://en.wikipedia.org/wiki/Spam_%28electronic%29#History