In my area, this is normal. I'm a mail carrier. So there are two different types of delivery, mounted and walking. Mounted means the boxes are all on the curb and you don't need to leave the vehicle to deliver unless the parcels are too big to fit in the box. Walking is what this house is, where the box is on the property and the carrier walks up one side of the street and down the other side back towards where they parked their mail vehicle. In my experience, location of the mailbox in that case varies wildly. Some are like this house, some boxes are right next to the sidewalk, some are inside the residents' garage, some are in their entryway and you have to open their outer door to deliver.