Nifty, but... https://lifehacker.com/build-a-mailbox-alarm-that-sends-you-a-text-whenever-yo-1394293178
As a former mailman, there are all sorts of weird contraptions people use. The most common one was this thing where a flag would pop up out the back when you open the front, so you can see from the house the mail has arrived. It scared the bejesus out of me the first time I opened it. I have found all sorts of crazy things in mailboxes from dead squirrels to used condoms to stacks of money.
really curious about that list of bizarre things...I feel like an epic story is behind the condoms and stacks of money lol