Hate Letter

A letter or email that serves the sole purpose of conveying a hateful (usually deserved) message.

Example of a Hate Letter:

Dear boyfriend,

I'm breaking up with you because you're a disgusting, sexist pig and I can no longer bear to associate with you. I hope you fall off a cliff...and die.

All the best,

your EX girlfriend.

P.S. I will be telling everyone I know that you rape puppies.