Send a message by carrier pigeon. It flies at 110 mph and takes about a day to cross the country, and there is no way to hurry it.
The route is real. Los Angeles to New York is 2,445 miles, which at pigeon speed is about 22 hours. The bird leaves the moment you press send and declines to hurry.
You can watch it the whole way. Every pigeon currently in the air appears on a globe you can spin, and you can follow any of them home, though you cannot read what they are carrying.
Nineteen things can go wrong on the journey. A bagel may be found. A fight may be lost with a reflection in a hubcap. The message always arrives, late, with an apology.
There is no account and no sign-up. Whoever you send the link to is the only person who can read the note, and everything is deleted after seven days.
You can pay to make one go faster. A jetpack is then issued.
A message carried by pigeon, at 110 mph.