New Zealand's largest postal sector union, the Engineering, Printing and Manufacturing Union (EPMU), says cutting the number of delivery days won't increase New Zealand Post's revenue.

The EPMU, which represents 4,500 New Zealand Post workers, including 2,500 Posties and mail sorters, says the answer is to increase the SOE's income.

"The challenge for New Zealand Post is to increase the number of small, higher revenue generating items that it delivers, such as letters, packets, small parcels and tracked items," says EPMU national postal coordinator Anna Kenny.

"Delivering post on fewer days should not be at the expense of cutting wages, especially when most New Zealand Post delivery staff work six days a week," she says.

"If postal deliveries were to be cut to alternate days, hundreds of posties and mail sorters would probably lose their jobs or have their work hours reduced to make them part-time," she says.

"This would also reduce the quality of service, increase unemployment and shrink the economy."

"In the meantime our members are playing there part by continuing to embrace new technology and training, and actively working to build efficiencies into the New Zealand Postal Delivery Service."