Canada Post says protesters blocking mail from flowing in and out of one of the country's busiest postal hubs are violating a court order.

The protesters rallying outside of the facility in Mississauga, Ont., are largely members of the Canadian Union of Public Employees acting in solidarity with postal workers who were legislated back to work last week.

The back-to-work legislation was passed on Monday following about five weeks of rotating strikes from the Canadian Union of Postal Workers.

CUPE says 19 protests are scheduled this weekend at facilities across the country, allowing workers to enter, but not letting mail out of the plants.

The Ontario branch of that union says the protesters have been served with an injunction, but they still plan to protest in solidarity with the postal workers.

The injunctions were granted by courts in Ontario, Alberta and British Columbia, prohibiting anyone from obstructing or interfering with people or vehicles entering or exiting its facilities.