At first, make sure you've installed Shopify Email App.
A tracking link can be added to your Shopify Email App templates so that your customers can track their parcels on your store tracking page by clicking the tracking link in the emails.
Step 1
Go to the tracking page in your store and copy the page URL
Step 2
Open the Shopify Email App and select the template you want to edit.
Step 3
Select the button in the email template you want to add a tracking link. Paste the URL that you've copied in step 2.