There will be "significant job losses" at NZ Post as it moves to deliver mail alongside courier parcels.

"The way we deliver mail in the future will look very different and we know our future workforce won't be the same size and shape as it is today," NZ Post chief executive David Walsh said.

"This decision means that there will be significant job losses in existing mail delivery, processing and support roles."

Over time, having two separate delivery networks will no longer be commercially viable, he said.

NZ Post has been consulting with employees and unions on reducing the number of roles involved in mail and has today confirmed its decision to progressively stream mail into its parcel network.

The Postal Workers Union had made a counter proposal in February.

It said the NZ Post plan will make deliveries slower.

"Since this is a long-term plan, no employees are directly affected by the move to one delivery network right now and our focus is on supporting our people with this change," Walsh said.

"Twenty years ago New Zealanders sent over 1 billion mail items in the year, which has decreased dramatically to around 220 million mail items in the current year, and we predict that this will decrease to about 120 million items by 2028.

"Mail decline isn't unique to New Zealand. Postal services around the globe are responding to the same changes in communication and are focusing on the challenge of maintaining a service that has high operating costs and very low usage.

"We need to continue to make hard decisions about our future as we evolve to meet the needs of New Zealanders."

Staff affected by redundancies and the change over will be supported by the Just Transition support programme recently signed with the E tū union, Walsh said.

Main image (RNZ/Richard Tindiller)