Blackcart uses EasyPost to handle shipment tracking and return label generation for Try Before You Buy orders.
As part of your onboarding requirements for Blackcart, you will need to ensure that your carrier account has been successfully added to EasyPost. Steps for adding your carrier account to EasyPost will differ depending on which carrier you use.
Canada Post Requirements
The Canada Post integration with EasyPost is unique compared to other carrier integrations as Canada Post requires that you log into their website when adding the EasyPost carrier account in order to effectively authenticate. Note that this is a different workflow than most other carriers where you would instead just add the carrier credentials into your EasyPost account directly.
How to add Canada Post to your EasyPost Account
Step by step instructions for adding your Canada Post account to EasyPost can be found in this EasyPost article, Setting up your Canada Post Account.