Here are some of the things that inspire me!
Letter Writers Alliance
Snail Mail Love
Oh Happy Day
Oh So Beautiful Paper
Snail Mail: Rediscovering the Art and Craft of Handmade Correspondence
Always First Class: The Pleasure of Personal Letters
Good Mail Day
Little Book of Lettering
I could go on and on about things that inspire me, but this is a good starting point! I hope all of these inspire you a little bit today!