If you take a package to a Canada Post location and find they reject the shipment, this is caused by incorrect scanning of the shipment by the postal worker.
Should you run into this situation and are shipping a domestic shipment, Canada Post suggests that postal workers select "Supplier Account" as payment method. This will allow the domestic packages to be accepted without error. If you are shipping an international shipment, Canada Post's guidance is for the clerk to contact the Retail Help Desk for support.
If you did run into this problem at a Canada Post location, please reach out to the Shippo support team at email@example.com with the Post Office location and the tracking number of the shipment.
Canada Post is working to re-communicate these recent changes and this information will help us work faster.