Unlike in the UK, post isn't delivered through the letterbox in your door here. It is more like the American system of a mailbox on the street. Now my parents don't have a letterbox in the door and postman always used to leave the post under a rock in the porch.
Mum and Dad decided that a New Zealand plastic postbox would look great in front of the house. This is despite the fact they live in a thatched cottage in a beautiful valley in Dorset. But I guess there are a lot of plastic postboxes in beautiful places in New Zealand too.