NZ Post has signalled a price increase for sending letters from early 2022 as mail size continues to decrease.
An NZ Post spokesperson said the postal service will "begin transitioning to a commercially sustainable model" for mail delivery.
However, NZ Post said mail size has continued to decline as more people communicate online.
Twenty years ago, NZ Post said the service delivered over 1 billion mail items annually, but a spokesperson said currently about 250 million items are delivered.
Due to this rapid decrease, NZ Post has announced a price increase in sending letters.