Penemies

[pen-uh-meez]
Pen Pals + Enemies
noun

1. Two or more people who write to one another (probably out of obligation) who do not like one another. The opposite of a pen pal.

Ex. "Dear Stanley,
I was thoroughly upset by your last correspondence which implied that you fancied a night alone with both my mother and sister but Mrs. Applebaum is forcing me to write you so that I may practice my cursive.
Die.
Die.
Die.
Die.
My, I'll be good at those capital D's by the end of this.
Rot in hell,
Isabelle"