From The Art and Popular Culture Encyclopedia
Hate mail (as electronic, postal, or otherwise) is a form of harassment, usually consisting of invective and potentially intimidating or threatening comments towards the recipient. Hate mail often contains exceptionally abusive, foul or otherwise hurtful language.
The recipient may receive disparaging remarks concerning the subject's ethnicity, sexuality, intelligence, political ideology, or sense of ethics. The text of hate mail often contains profanity, or it may simply contain a negative, disappropriating message.