About 55,000 Canada Post workers went on strike Friday after their union said it had failed to reach a pay deal with the postal operator in the run-up to the holiday season.
The union is demanding, among other things, wage increases in line with inflation, cost-of-living adjustment payments to be rolled into the basic wage rate, and safe working conditions.
The union had issued a three-day strike notice to Canada Post earlier this week.
"After a year of bargaining with little progress, postal workers made the difficult decision to strike," the Canadian Union of Postal Workers (CUPW) said in a statement.
Canada Post said in a separate statement that its operations would shut down during the strike, adding that mail and parcels would not be processed or delivered, and some post offices would be closed.
In recent months, Canada's Liberal government has stepped in twice to halt labour disputes.
Earlier this week, the government ordered an end to disputes at Canada's biggest ports and in August, it put an end to work stoppages at the country's two largest railway companies.
The country's Labour Minister Steven MacKinnon said on Thursday night that he has formally appointed a special mediator between Canada Post and the workers' union.
"Canadians need them to reach an agreement," he said in a post on social media platform X. "We are making sure that these two groups have everything they need to reach a deal."
—Reuters