I wrote Pigeon in the Go programming language as a learning project and as an experimental communication platform.
It's just like a regular messaging platform, except that messages only appear in the recipient's mailbox after an artificial two day delay period.
Yep, we're using modern internet tech to emulate snail mail. Retro nostalgia culture gone amock!
Feel free to sign up and give it a try. I wouldn't count on any of your messages being saved long term, though I'll make sure and give you a copy if you happen to join.
See more of my work on my github account and my personal website.