it seems like I found a bug in the way shopify handles tracking links in the fulfillment of orders.
What is happening?
When I fulfill an order, and put in my tracking link directly it works out just fine as it should. However if I change the tracking after I marked the order as fulfilled, Shopify changes the tracking link of the order. In my case I choose DHL as a shipping-service but Shopify displays the tracking-link for Australian Post. The E-mail that gets sent out has the wrong tracking-link aswell.
Here's how to reproduce it:
• Mark an order as fulfilled and put in your tracking number. For testing purposes you can pick this one here: 00340434296182306058 (DHL). Also tick the box that the buyer should be notified.
• Save it and check the order and e-mail. Both should display the correkt tracking-link to DHL
• Now try to change the tracking-information of the fulfilled order again. You don't have to change anything, just hit save again.
• The tracking link in my case is now wrong and redirects the user to Australian Post instead of DHL