The union representing postal workers say deliveries will take longer. (Andrew Vaughan/Canadian Press)

Postal workers warn that a new system for delivering mail will mean some people will have to wait for their letters and packages.

Canada Post is phasing out its system of using three separate trucks to drop mail off at collection boxes, deliver parcels and pick up outgoing mail.

As of Monday, letter carriers in Halifax will use one van to perform these tasks. It will be the first test of the new system in the East Coast.

In Winnipeg, where the plan is already in effect, the mail arrives much later, according to the Canadian Union of Postal Workers.

"When they first implemented the modern post in Winnipeg, it was not unusual to see letter carriers out at 10 o'clock at night. Every other place it's been initiated, it's a 10-to-12-hour workday," said Trevor Beckerson, president of the union local in Nova Scotia.

Anick Losier, a spokeswoman for Canada Post, said the mail will always arrive by 5 p.m., though the time of delivery during the day could change.

"Essentially, you as a customer will be receiving the mail every day the same way, but not at the same time necessarily," she said.

The Crown corporation expects to save $250 million over six years with its new delivery system.

Beckerson said for workers, the new system means job losses of up to 30 per cent. But Losier said any cuts would come as a result of employees retiring.