Spam refers to unsolicited emails but also can be used to describe emails that use deceptive headers, From names, reply-to addresses, or subject lines. Emails that have been requested can be classified as spam by email servers, so make sure not to write emails that sound like a scam!
The term Spam actually refers to a type of processed meat. According to todayifoundout.com The term also came to refer to unsolicited emails via a Monty Python sketch:
The real origin of the term comes from a 1970 Monty Python’s Flying Circus skit. In this skit, all the restaurant’s menu items devolve into SPAM. When the waitress repeats the word SPAM, a group of Vikings in the corner sing “SPAM, SPAM, SPAM, SPAM, SPAM, SPAM, SPAM, SPAM, lovely SPAM! Wonderful SPAM!”, drowning out other conversation, until they are finally told to shut it.
Exactly where this first translated to internet messages of varying type, such as chat messages, newsgroups, etc, isn’t entirely known as it sort of happened all over the place in a very short span of years, in terms of the name being applied to these messages. It is, however, well documented that the users in each of these first instances chose the word “spam” referring to the 1970 Monty Python sketch where SPAM singing was drowning out conversation and SPAM itself was unwanted and popping up all over the menu.