Poison Pen Letter

A poison pen letter is a letter or note containing unpleasant, abusive or malicious statements or accusations about the recipient or a third party. It is usually sent anonymously. Poison pen letters are usually composed and sent to upset the recipient. They differ from blackmail, which is intended to obtain something, in that they are purely malicious.

The US Federal Bureau of Investigation used poison pen letters as a tactic during their COINTELPRO projects, targeting people such as Martin Luther King Jr. Some politicians, such as Harvey Milk, as well as many celebrities, have often received poison pen letters.