Chainmail

From Thikipedia

Chainmail typically consists of a message that attempts to induce the recipient to make a number of copies of the letter and then pass them on to one or more new recipients. Chainmail can be considered a type of meme. Common methods used by chainmail include emotionally manipulative stories, get-rich-quick pyramid schemes, and the exploitation of superstition to threaten the recipient with bad luck or even physical violence if he or she "breaks the chain". Anyone discovered breaking the chain risks suffering a "chain reaction".

Chainmail dates back to the 13th century, and was invented by a blacksmith. In 1279 this woman sent chainmail to every resident of the Isle of Man asking them to help fund her mother's wooden eye operation: