After having negotiated a discounted rate with USPS, you now can activate the shipping in your Shopify store with USPS. And the discounted rate will be displayed when your customer checkout.
Step 1: Get a USPS user ID
Step 2: Register USPS
You will use the user ID to access to package tracking, service delivery standards APIs and rate with USPS when registering.
That’s all. Registering with USPS is so simple so all of you can do it yourself.
Thanks for reading!