Dad Joke.com
How does a vampire start a letter?Tomb it may concern
Definition.com
Letter writing is wonderful when old. One of the pleasures of reading them is the knowledge that they need no answer.
Meme.com

Definition.com
Letter writing is one of night's objects. Nine-tenths of the letters in which people speak unreservedly of their inmost feelings are written after ten at night.
Definition.com
Letter writing is a swell way to keep from working and yet feel you've done something.