I ran my own blog from November 2006 till October 2014. All posts are still online, but I don't have time to update it anymore. Please note that all images and media files have been removed when the backup was moved to a new host in early 2016. Enjoy!
E-mail was invented at the MIT in the mid 1960s as a communications tool for the Compatible Time-Sharing System (CTSS), several years before ARPANET (which later became the Internet) was started. It was used on several operating systems during the 1960s, including MIT's CTSS and SDC's Q32, and it was also a basic feature in the MULTICS system (the predecessor of UNIX) which was being developed around the same time.
About 30 years earlier, the Hormel Foods Corporation was facing the problem that one of their major products, the Hormel Spiced Ham, was losing market share. They decided to re-brand the product, and on July 5, 1937, it was relaunched as "Spam", a name chosen from multiple entries in a naming contest ("Spam" could in fact be considered to by an abbreviation for "SPiced hAM" or "Shoulder of Pork and hAM", depending on which source you rely). Many jocular backronyms have been devised, such as "Something Posing As Meat" and "Spare Parts Animal Meat" for example.
Spam remained a simple consumer product until December 15, 1970 (around the time e-mails became popular on time-sharing systems), when the famous british comedy group Monty Python (consisting of Graham Chapman, John Cleese, Terry Gilliam, Eric Idle, Terry Jones, and Michael Palin) first televised their "Spam" sketch. In the sketch, two customers are trying to order a breakfast from a menu that includes Spam in almost every dish. No matter what they tried to order, they always got the undesired Spam ("Spam, Spam, Spam, Spam, Spam, baked beans, Spam, Spam, Spam and Spam"). The sketch became immensely popular among Monty Pythons fans.
The first time unsolicited mass mail has been reported was in 1971, when Peter Bos used CTSS MAIL to send an anti-war message to all system users, although this only affected users on the MIT campus. The same year (still 1971) Ray Tomlinson initiated the use of the @ sign to separate the names of the user and their machine. During the 1970s the popularity of e-mail significantly increased, and it became the killer app of the ARPANET.
On May 3, 1978, a DEC marketer named Gary Thuerk decided to use e-mail as a marketing tool and sent a mail about a Dec-20 computer demo to a large number of APRANET users (e-mail addresses had been collected using a printed list of all APRANET users). This was the first documented case of unsolicited mass mailing, which also clearly violated the APRANET policies. Gary Thuerk apparently got into some trouble because of his actions, and no further mass mailings appeared after that.
Everything remained quiet for about 10 years. On May 24, 1988, a student called Rob Noha who needed some cash posted a message in as many newsgroups as he could find to raise money. Around the same time, USENET was flooded by a "MAKE MONEY FAST" chain letter. But these were still single and rare events.
On March 31, 1993, Richard Depew unintentionally posted hundreds of USENET messages due to a bug in a software he created. The same message was repeated over 200 times in a single thread, and thus some users called it "Spam", as it remembered them the famous Monty Python sketch. This was the very first time to word "Spam" was used for an e-mail message, and apparently it was Joel Furr who used it first. Richard Depew apologized for the unintentional mass mailing, and he then also used the term "Spam" when doing so.
The first fully intentional spamming of the USENET happened on January 18, 1994 when Clarence Thomas, a system administrator at Andrews University, posted the message "Global Alert for All: Jesus is Coming Soon" into every single newsgroup. Only a few months later, in April, Laurence A. Canter and Martha S. Siegel posted the "Green Card Lottery - Final One?" spam to every group in the USENET, which kicked off an entire wave of spams.
And this is where the story ends, as we all know what happened after that... More than six billion cans of Spam have been sold so far, but a much larger number of spam mails have been sent by spammers. By the way, The Hormel company always supported the Monty Python sketch (great marketing at no cost), but they were never happy with the use of the word spam for junk email.