Idiom of the day :- Poison-pen letter

Idiom of the day :- Poison-pen letter

Usage, examples and definition of the Idiom :-

Poisonous things can injure or kill. While a person writing a poison-pen letter to someone doesn’t kill, he or she often succeeds in causing injury for such letters contain evil and untrue things about that person. They might even contain threats. Writers of poison-pen letters are usually too cowardly to sign their names on them.