You are lucky that is your issue. My mail carrier doesn't close my post box. It's not difficult.
After one winter - when the snow melted, I found al kinds of letters wet, mushy, and scattered around my yard.
Yes, I went in and complaingned. Did it do any good? LOL! ROFLMAO! no.
I work for a RR. I am gone 2 days at a time. When I get home, I expect my mail to be there.
It is, just not always in my box if the wind blows. I live in a small town of 3500. You would think that they could get their collective "stuff" together.
May have to complain again soon.