The government has agreed to a steep reduction in the six-days-a-week service from 2015 following lobbying from New Zealand Post. The company said reduced delivery days would result in significant job losses among its 2000 delivery staff.
The move could foreshadow similar changes in other developed nations as businesses and residents increasingly move online to communicate and pay bills.
From June 2015, New Zealand Post will be required to deliver mail three days a week in urban areas and five days a week in rural areas. About 12% of customers live in rural areas.
Brian Roche, chief executive of New Zealand Post, said: "People just don't look at their letter box any more as their principal form of communication."
Communications minister Amy Adams added: "Around the world, postal volumes are declining. In New Zealand, this is at a rate of about 8% per annum."