Spam

Spam, unsolicited e-mail, the electronic equivalent of junk mail. People usually send spam in order to sell products and services, to draw traffic to Web sites, or to promote moneymaking schemes. Unlike physical junk mail, spam does not stop if it is unsuccessful. When marketing departments send junk mail they incur some expense, so give up if they do not succeed. Spam costs virtually nothing to send and so it persists, whatever the recipient does.
Spam can easily be confused with legitimate bulk e-mail. According to Mail Abuse Prevention System (MAPS), an electronic message is regarded as spam only if the recipient's personal identity is irrelevant because the message is equally applicable to many others; the recipient has not granted permission for it to be sent; and the message appears to the recipient to give a disproportionate benefit to the sender.
Spam has become a big problem over the past few years as it consumes large amounts of the recipient’s time and Internet capacity. It is also an enduring problem as it is virtually impossible to determine where it originates. The first spam was sent as long ago as 1978 by a Digital Equipment Corporation sales representative to advertise a computer equipment demonstration.
The initial defence against spam was to block mail from domains that are known to be senders but it is relatively easy for spam senders to send from a new domain. The most effective measure now available is to use one of the e-mail filters on the market that saves the user from having to manually sift though his or her inbox.
Legislation introduced in the European Union in December 2003 makes it a criminal offence to send spam unless the recipient has agreed in advance to accept it. Similar legislation was signed into law in the US in the same month.