As a mail man I hated those tractor boxes.   The mail gets caught as the box narrows and it's tough to put in, especially when you have people that only pick up their mail once a week.   And worse is the location of the flag.   It's back so far that it's hard to reach and lower.   Another carrier only told me the best thing about those boxes is they are plastic and usually don't survive an encounter with the snow plow.   Sorry to be so blunt, but I'm not a fan of them.