We had a similar issue once. We learn that the bottom right corner of an envelope includes an invisible code for the computer to send the letter to us (the first place it was sent). A postal worked told us to go over the lower right of the envelope with a pen or pencil to create a box about a quarter of an inch high and a couple inches in length to block the code.
But aren’t they still reading the return address label? It clearly shows the wrong number. I’d think it’ll still end up in our little box again. Right when I’m getting lots of mail for annual membership!