I have searched this community and a lot of Googling and have not found a working solution for what I need so I could use your help please. Due to my customer's requirements, I need a PHP based solution for retrieving orders from Shopify and sending tracking numbers to complete the order and send the email. We are using an external 3rd party fulfillment company. I have the retrieving orders part working so the basics of authorization, etc. are handled. It was done using PHP CURL GET. But trying to use a similar CURL POST is not working as I need.
What I get as a response starts with "HTTP/1.1 303" and ends with "You are being redirected."
Here is what I am using minus the store specific parts. I have tried using tracking_numbers and tracking_number with same result.