Poison pen letter
From Wikipedia, the free encyclopedia
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 addressee and, in some cases, maybe to make them change a course of action.
With the advent of e-mail and the general decline in letter writing, poison pen letters have become something of a rarity.