Read Thread: Search for Letterboxer by Location
I've experienced a PA Drink & Ink & Drink event where slack boxing turned into slosh boxing.
"Let's meet at this cool bar... that happens to be in a tree."
You could send the person a email if you wanted to or you could see where there boxes are idk those are the only things that I could think of. It's probably for the better that you can't see there location.