New Zealand Post will cut mail delivery in urban areas to three days a week from July.

The State Owned Enterprise has been telling staff of the move today, which follows a change to its deed of understanding with the Government in 2013.

The move is a step to protect the organisation from a fall in mail volumes which is hitting profitability.

Mail and communications chief operating officer Ashley Smout confirmed standard mail would be delivered every second day to households in urban areas starting from July in larger towns and cities.

Over the following two years it would be rolled out to smaller centres.

"The way we plan to roll out these changes means we will continue to meet our delivery targets for standard letters," he said.

"We're confident customers will see very little, if any, difference in the services they receive from New Zealand Post as a result of these delivery changes."

Smout said that despite the changes, NZ Post's target of 95 per cent delivery of standard mail within three days remained in place, while priority mail and courier delivery would continue to operate six days a week.

Alternate delivery days will be tested in parts of Auckland centred on Ellerslie "to fine-tune the changes before the July rollout" NZ Post said in a statement.

Rural delivery would remain "largely unchanged" as would the targets for FastPost.

Meanwhile NZ Post said it would hold larger trials in New Plymouth of vehicles to help it deliver an increasing proportion of parcels.

"We're making these changes in response to people sending fewer letters. Our analysis shows the average household receives letters just three days a week," Smout said.

GOVERNMENT APPROVAL REQUIRED

When the changes to the deed were signalled by the Government at the start of 2013, Communications Minister Amy Adams warned of a looming plunge in postal volumes.

"During the last 10 years mail volumes have dropped considerably, with 265 million fewer items being posted each year compared to 2002," Adams said.

"Within five years, mail volumes are forecast to be nearly half what they were in 2002. In light of those significant reductions in mail volume, New Zealand Post is seeking to make changes to the Universal Service Obligations it is bound by."

Adams said the changes would require government approval, and public feedback would be sought.

"In deciding whether to accept or reject the proposal or seek to negotiate a compromise, I will look to balance the interests of postal users with the need to ensure a financially-viable postal service," she said.

Today in Parliament, Adams said she doubted the changes would make a material difference to households.

"The reality is letter volumes have dropped exponentially. That's happened all around the world. It's probably worse in New Zealand because our population base means these things are felt sooner rather than later," she said.

Alternative delivery dates, where a household would receive post every second day, mean letters would only arrive at most a day later than they do now.

"Most things we get in the mail really are not that time sensitive that one day is going to make a critical difference."