I love handwritten letters. Scratch that, they don't even have to be handwritten, even typed and printed off is nice. Really, anything in the mailbox attached to my house that's not junk, a bill, or "The Watchtower" is something I appreciate.
When the boys were young, I used to write 30 letters a month. I wrote to my grandma once a week, X's grandparents once every second week, and pretty much everyone else who doesn't live here once a month. I get that not everyone enjoys writing as much as I do, so I really love those letters that wind up in my mailbox.
Sometimes BFF will send me a beautiful notecard. I'll save it until all the other mail has been taken care of, carefully slit open the envelope, gently remove the card, run my hand over the top to feel the texture, open it with the anticipation of reading all that's going on in her life...to find nothing but a drawing of a guy smoking a cigarette (it's all she knows how to draw). And I love it, because she thought of me.
Sugarplum is amazing for sending stuff. Every special day requires a note from Sugarplum. Valentine's Day, Halloween, Father's Day. Sometimes, a special day is the day she tidied a cupboard and found notecards she forgot about.
I hope you all have a personal-letter-in-your-mailbox kind of day!