I see your problem right off the bat. You think of that mail box as yours, it is not. By law the U.S.P.S. owns that mail box after you buy it and install it to receive U.S. mail.
As I recall, mail delivery was considered voluntary back in the day. If you didn’t install a box, the carriers would just leave your mail at the local branch.
By that rationale, I think I’m going to take down my mailbox and see what happens.