Email spam, also known as junk email, is a type of electronic spam where unsolicited messages are sent by email.
What is Email Spam?
Many email spam messages are commercial in nature but may also contain disguised links that appear to be for familiar websites but in fact lead to phishing web sites or sites that are hosting malware. Spam email may also include malware as scripts or other executable file attachments (trojans). Spam is named after Spam luncheon meat by way of a Monty Python sketch in which Spam is ubiquitous, unavoidable and repetitive.
Email spam has steadily grown since the early 1990s. Botnets, networks of virus-infected computers, are used to send about 80% of spam. Since the expense of the spam is borne mostly by the recipient, it is effectively postage due advertising. This makes it an excellent example of a negative externality.
The legal status of spam varies from one jurisdiction to another. In the United States, spam was declared to be legal by the CAN-SPAM Act of 2003 provided the message adheres to rules set by the Act and by the FTC. ISPs have attempted to recover the cost of spam through lawsuits against spammers, although they have been mostly unsuccessful in collecting damages despite winning in court.
Spammers collect email addresses from chatrooms, websites, customer lists, newsgroups, and viruses that harvest users' address books. These collected email addresses are sometimes also sold to other spammers. The proportion of spam email was around 90% of email messages sent.