Affected New Zealand Post workers in Northland may be redeployed to other areas once the FastPost service stops operating from January.
NZ Post this week announced FastPost service would no longer be available following a review of the company's priority mail network.
The change will force people to use courier products as an alternative way of sending priority mail.
Currently only 1 per cent of all mail throughout the country is sent using FastPost and during the last year the number of items sent has declined by 23 per cent.
"The amount of all letter volumes continues to decline significantly, at a rate of approximately 60 million items a year and despite ongoing cost reductions, this change is necessary," NZ Post said.