A place where all letters are available to be read (and kept) by those who most need them. Sort of like a "Post Secret" - letters addressed to the deceased, missing, or otherwise written thoughts that can't find their audience.
1317-2 Takumacho Awashima
Mitoyo, Kagawa 769-1108
Japan
I miss writing letters, the concreteness of a pen & paper, or an old clattering Underwood Typewriter. I might have to use this.
(via FutilityCloset.com) && a more in-depth explanation on the Wikipedia: https://en.wikipedia.org/wiki/Missing_Post_Office