Today I received the first 'poison pen' letter I've ever seen. https://en.wikipedia.org/wiki/Poison_pen_letter
It was anonymous, of course. It wasn't targeted at me, it was addressed to my P.O. box, so everyone with a box likely got one.
The target of the letter was someone I don't know personally. (Small town, so I probably met her at some point.) The letter was an angry rant against this person, urging recipients to contact Child Protective Services on her.
I'm left feeling rather unsettled–I don't like this shit.