New Zealand Post says mail volumes fell at their fastest ever rate last year, despite a rise in the number of parcels being sent.
The fall is largely due to banks and utility companies sending more bills electronically, but on the flipside, the growth in online shopping has put more parcels in the mail.
New Zealand Post chief operating officer Ashley Smout said it processed up to 200,000 parcels a day in the lead-up to Christmas; but overall mail volumes fell by about 9 percent in 2014 - the biggest fall yet.
Mr Smout said the decline reinforced the need for restructuring such as cutting residential mail deliveries from six to three times a week, which will happen in July.
"We'll deliver mail and urgent mail and parcels six days a week, but standard mail will go from, in residential areas, from six days a week to three days from first of July."