We had a problem with ours getting smashed by vandals, apparently with baseball bats, years ago at one plant. The mechanics built a new one out of 3/16" spring steel, reinforced with 3/4" square spring steel bars. I would have loved to have a video of the first time they whacked it with a bat
Similar situation, back in my high school days we had certain teacher who defined the word P.R.I.C.K. to the extreme!
He lived in the country and as you can well imagine his mail box was considered a target of opportunity for nearly every student he screwed over. Bricks, cinder blocks, even bowling balls were launched from vehicles driving by a pretty good clip.
He ended up having a box built from 1/4 plate similarly to the description above, after that the projectiles I mentioned only scuffed the paint.
(Honest Injun, I was not one of the perps) but I did witness the aftermath a time or two when the word got out.