Our neighboorhood (twenty 5-acre lots) did the same a few years back due mostly to convenience. Our gravel private road is a mile long, and this gives the lazy mail lady a single place to put the mail. I think the post office actually gave the homeowners association some sort of kick-back for the convenience. The original box that was purchased was broken into once before one of our neighbors took it to his shop and super-modified it (to the tune of plate all around). We've got it mounted in a concrete slab at the entrance to our road, and so far, so good (3 years now). Now if we could just get the lazy mail lady to get her a** out of her jeep to deliver the packages that are too big for the box

...instead, she just drives up the drive way and tosses it out her window in front of the garage door. Or, better yet, if she doesn't feel like driving the extra 1/4 mile to the front of the garage door, she just leaves a little notice in the mail box and we have to go to the post office to pick it up.