I’ve been here twice. My high school teacher lives around here; a group of us in his homeroom had an adventure on his pontoon boat.
If you can’t make it here, that doesn’t mean you can’t get a Hell postmark on your mail. What you do is mail a package to the postmaster of Hell, enclosing the letters (stamped properly of course with postage), and requesting that they remail it with a postmark. Lots of places will do this for you.