Hope that was sarcasm. I’ve has USPS literally stuff over-sized parcels into my mailbox. I had to replace an old aluminum mailbox, because they crammed in a box that warped the structure and the door wouldn’t close.
During the holidays, these guys are probably so over-worked that they don’t want to deal with people. I’ve had FedEx AND UPS leave packages on my doorstep without so much as a push of the ringer. Just drop and go.
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.
I had a sub mailman leave he box open and everything, including a birthday check for my daughter, got soaked.
Just last week I ordered a new keyboard for my laptop. The package was CLEARLY marked "fragile" and "do not bend". So the mail-guy shoves it into my mailbox to the point that it put a 30 degree bend in it near the last quarter of the board! I managed to get it un-bent (with some care and time), but even if I would have had to send it back, the guy cost me a lot of time and effort...