Letterbox delivery is a competitive advantage because it saves money on delivery; the driver can often drop letters off in a mail room at a multi-unit dwelling,

Letterbox delivery is a competitive advantage because it saves money on delivery; the driver can often drop letters off in a mail room at a multi-unit dwelling, or by the road in the suburbs/rural areas. We're only talking about first-class mail here, so a 6x cost advantage in first-class mail is very important.