Roche said mail delivery is barely breaking even and would begin losing money if not for the cutbacks, which he hopes will enable the service to remain viable for years to come. He said customers wanting daily mail deliveries will be able to sign up for a new courier-type service at a premium.
He said the changes will result in significant job losses among the country's 2,000 or so postal delivery workers.
Mail volumes in the nation of 4.5 million people have dropped by a quarter in the last decade and the decline appears to be accelerating.
"Around the world postal volumes are declining," said Communications Minister Amy Adams. "In New Zealand, this is at a rate of about 8 percent per annum."
In the U.S., the Postal Service has struggled for years with declining mail volumes. The service has tried to end its Saturday mail delivery but has been met with resistance from federal lawmakers.
In a contentious move in Britain, the coalition government this month privatized the country's 500-year-old Royal Mail. It promised six days a week service would continue.