The growth of unsolicited e-mail imposes increasing costs on networks and causes considerable aggravation on the part of e-mail recipients. Provided a spammer has access to a fast network (or increasingly to a botnet), spam costs the sender almost nothing and although only a tiny fraction of users will respond to a spam message, sufficiently vast numbers of emails are sent that the rewards far outweigh the costs.
Nearly 85% of all emails are spam.
That translates into an average daily volume of 122.33 billion messages globally.
Such is the torrent of spam that internet service providers and companies have to buy far more bandwidth and storage than they will ever need for legitimate purposes - and spam contributes to global warming because of this.
The History of Spam
The history of spam is one that is closely tied to the history and evolution of the Internet itself.
Early internet development was by people who trusted one another. Back in the 90s the internet was the domain of geeks and scientists. Therefore contact via e-mail was made simple and convenient.
But as more people and companies have come to make use the internet, e-mail has become a tool that anyone can use for good or bad.
Here is a timeline that may interest you:
1971
RFC 733: Mail Specifications
1978
First email spam was sent out to users of ARPANET – it was an ad for a presentation by Digital Equipment Corporation (DEC)
1984
Domain Name System (DNS) introduced
1986
Eric Thomas develops first commercial mailing list program called LISTSERV
1988
First know email Chain letter sent
“Spamming” starts as prank by participants in multi-user dungeon games by MUDers (Multi User Dungeon) to fill rivals accounts with unwanted electronic junk mail. (But at that point it was not called 'spamming').
1990
ARPANET terminates
1993
First use of the term spam was for a post from USENET by Richard Depew to news.admin.policy, which was the result of a bug in a software program that caused 200 messages to go out to the news group.
The term “spam” itself was thought to have come from the spam skit by Monty Python's Flying Circus.
In the sketch, a restaurant serves all its food with lots of spam, and the waitress repeats the word several times in describing how much spam is in the items. When she does this, a group of Vikings in the corner start a song: "Spam, spam, spam, spam, spam, spam, spam, spam, lovely spam! Wonderful spam!" Until told to shut up. Thus the meaning of the term: something that keeps repeating and repeating to great annoyance.
1994
January, first large scale spam distributed across USENET – “Global Alert for All: Jesus is Coming Soon” was cross posted to every newsgroup 1994 April, spamming became business practice, two lawyers Canter and Siegel posted a message “Green Card Lottery – Final One?” to every news group possible
1997
US Federal Trade Commission (FTC) spam hearings
First SMTP hijacking – Simple Mail transfer Protocol (SMTP) is a sender push technology that delivered all messages without any sender requirement to provide an authentic return address.
First Relay hijacking - allows third-party relay of e-mail messages by processing email that is neither for nor from a local user, an open relay makes it possible for an unscrupulous sender to route large volumes of spam using network resources from unsuspecting providers
Paul Vixie creates Realtime Blackhole List (RBL) of spam sites 1998 DC ISOC Chapter of the Internet Society hosts meeting on spam 2000 Nigerian “419” email spam
2001
Code Red worm and Sircam virus infiltrate thousands of web servers and email accounts causing a spike in Internet bandwidth usage
2003
May 3rd – 25th anniversary of the first “spam” and the first time that the amount of spam email exceeded the amount of legitimate email
First spamming “botnets” appeared 2006 IronPort released a study (June 28, 2006) that found that 80% of spam emails originated from “zombie” computers. It also reported there were 55 billion spam emails sent in June 2006. Botnets sent from zombie computers are often used to spread e-mail spam. Most owners are unaware that their computer is being used in this way therefore the computers are called zombies.
2009
Majority of spam sent around the world was in English, however spammers started using automatic translations services to send spam in other languages.
2010
An estimated 88% of worldwide email traffic was spam (Symantec)
2011
Largest "botnet" on record (Rustock) that had infected over a million computers and had the capacity to send 30 billion emails a day was taken down in March through cooperation and actions between industry and various governments
Just being bombarded with adverts you don't want is annoying - but 'spoofing spam' is being bombarded with e-mails that pertain to come from someone you know or trust - but in reality they come from a 'threat actor'.
Spam
RFC 733: Mail Specifications
Spoofing makes spam dangerous. 
