On May 3, 1978, the first spam message was sent via email. The culprit was Gary Thuerk, which sent propaganda material to 293 different addresses on what was then ARPANET (the precursor to the Internet, developed within the US Department of Defense).
The material sent contained an advertisement for new computers from DEC (Digital Equipment Corporation). Recipients of the initial spam were upset, but the whole promotion still led to an increase in sales of these computers. The name SPAM for such messages comes from a sketch by Monty Python, where it referred to a kind of canned dish, similar to a meat breakfast, that appears as an ingredient in all dishes in a restaurant.
Today, electronic spam accounts for 80-85% of all global email traffic. The leading spam generator in the world is the US (13.21%), followed by China (11.25%), Vietnam (9.85%), India (7.02%) and Germany (5.66%).