I’ve heard the same thing. I seem to remember that Jimmy Carter’s “secret code” was an old phone number of his wife.
When I really want someone to open a letter I send it in a big Fed-X envelope. I picked up on this from watching people in an office react when a Fed-X comes in.
If an asshole/petty thief sent a letter to a known-to-be non address, with a dead or false return address, is this fraud?
I don’t even know. He was one of those nuts who always had a better, and for some reason, sneakier, way to do everything and he got a real kick out of it.
When I was in college, a friend and I started using 1-cent stamps to exchange letters. Twenty of 'em (the first-class rate at the time), which would cover nearly half the envelope.
The postmark would only cover a few of them, so the recipient would then cut out the un-cancelled ones and paste them on the next letter, with enough new stamps to make up the difference. It wasn’t so much that we were too cheap to buy a 20-cent stamp; we pretty much did this just for a laugh.