# Chain letter

A chain letter is a message that attempts to convince the recipient to make a number of copies and pass them on to a certain number of recipients. The "chain" is an exponentially growing pyramid (a tree graph) that cannot be sustained indefinitely.
Common methods used in chain letters include emotionally manipulative stories, get-rich-quick pyramid schemes, and the exploitation of superstition to threaten the recipient. Originally, chain letters were letters sent by mail; today, chain letters are often sent electronically via email, social network sites, and text messages.

## Types

There are two main types of chain letter:
* Hoaxes: hoaxes attempt to trick or defraud users. A hoax could be malicious, instructing users to delete a file necessary to the operating system by claiming it is a virus. It could also be a scam that convinces users to spread the letter to other people for a specific reason, or send money or personal information. Phishing attacks could fall into this.
* Urban legends: urban legends are designed to be redistributed and usually warn users of a threat or claim to be notifying them of important or urgent information. Another common form are the emails that promise users monetary rewards for forwarding the message or suggest that they are signing something that will be submitted to a particular group. Urban legends usually have no negative effect aside from wasted time.
In the United States, chain letters that request money or other items of value and promise a substantial return to the participants (such as the infamous Make Money Fast scheme) are illegal.
Some colleges and military bases have passed regulations stating that in the private mail of college students and military personnel, respectively, chain letters are not authorized and will be thrown out. However, it is often difficult to distinguish chain letters from genuine correspondence.

## Channels
### Print

The oldest known channel for chain letters is written, or printed, on letters on paper. These might be exchanged hand-to-hand or distributed through the mail. Already in the nineteenth century, chain letters were known to have circulated among Muslim pilgrims going on the hajj to Mecca. Those chain letters promised blessings or curses and required replication. One notorious early example was the "Prosperity Club" or "Send-a-Dime" letter. This letter started in Denver, Colorado in 1935, based on an earlier luck letter. It soon swamped the Denver post office with hundreds of thousands of letters before spilling into St. Louis and other cities. In 1964, the head of the United States Postal Inspection Service ordered a nationwide crackdown on violators of postal fraud and lottery laws due to an increase of chain letters reported around college towns in the United States. The typical letters included a list of names and instructed the recipient to send money to the name at the top of the list, remove that name, add their own name to the bottom of the list, and forward the letters to two more people.

### Email

Some email messages sent as chain letters may seem fairly harmless; for example, a school student wishing to see how many people can receive their email for a science project, but they can grow exponentially and be hard to stop. Infamously, the salacious Claire Swire email spread in a chain-like fashion when its recipient sought to learn Swire's identity.
Messages sometimes include phony promises from companies or wealthy individuals (such as Bill Gates) promising a monetary reward to everyone who receives the message. They may also be politically motivated, such as "Save the Scouts, forward this to as many friends as possible" or a warning that a popular TV or radio show may be forced off the air. Some, such as the Hawaiian Good Luck Totem, which has spread in thousands of forms, threaten users with bad luck if not forwarded. One chain letter distributed on MSN Hotmail began, "Hey it's Tara and John the directors of MSN..." and subsequently claimed readers' accounts would be deleted if they did not pass on the message.
Another common form of email chain letter is the virus hoax and a form of cyberbullying.

### Web communities

Chain letters within social media platforms became widespread on Myspace (in the form of Myspace bulletins) and YouTube (in the form of video comments) as well as on Facebook through messages or applications. For instance, the chain post/email of Carmen Winstead, supposedly about a girl from Indiana who was pushed down a sewage drain in a fire drill, states that, "if you do not repost/send this to 10 people, Carmen will find you and kill you." Chain letters are often coupled with intimidating hoaxes or the promise of providing the sender with "secret" information once they have forwarded the message.