we have some friends who's son was blowing up mail boxes and the kid spent a good number of years in federal prison for the deed, they take it very serious, (wife thinks it was 8 years),
one Idea I heard about was to take a large box and put a small box in side it and cement in between the two,
around here the county will make you remove the post if it is "hazardous" so they will not injure or kill some if an accident happens, (no RR ties or 8" posts or steel posts filled with cement,
I finally ended up filling in an edge of the road and moving it back from the edge of the gravel road about 6 to 8 foot, safer for the mail car, and it has not been knocked down yet,
my situations I think were accidental, wide farm equipment,
A semi that missed the turn and took the mail box out and the water hydrant, down behind it, at night,
some guy not paying attention and drove right into it and into the ditch and up over the cross road, (kids aw it happen and said it was quite a ride)
come to think of it I think the county mower guy is nearly as hard on it as any one, LOL,