Chain e-mail

Chain e-mail is a term used to describe e-mails that encourage recipients to forward them on to someone else, the Internet versions of the chain letter.

Some e-mail service providers prohibit the use of their service for sending chain letters in their abuse policy, including Yahoo! and Comcast.

Chain letters may also qualify under other types of illegal activities, as in the case of a Ponzi scheme asking recipients to send money and forward the e-mail. They may be harmful, and contain trojans.

Chain letters are discouraged by RFC 1855.

Some may seem fairly harmless, for example, a grammar school student wishing to see how many people can receive his e-mail for a science project, but can grow exponentially and be hard to stop. They may contain false information, such as the famous "Forward this to everyone you know and if it reaches 1000 people everyone on the list will receive $1000" type e-mails. They may also be politically motivated, such as "save the scouts, forward this to as many friends as possible". Some recent chain e-mails say that a company "will stop its free email service if you don't send this message to X people". Some threaten users with bad luck if not forwarded.

Forwarding chain e-mail may increase a user's risk of getting viruses, and may also increase the amount of spam received, since participant's e-mail addresses are sometimes visible and may end up in the hands of spammers, either directly or via mailing lists archives on the web.

E-mails that are forwarded simply because they are enjoyed, such as urban legends or jokes or glurges are not necessarily under the chain e-mail category, although some chain e-mail is obviously humorous. Likewise, most spam is not chain e-mail as it doesn't typically ask recipients to forward the e-mail to friends.

http://en.wikipedia.org/wiki/Chain_e-mail