Hi @Kevin Gene Cole,
I'm here to take care of your query about customizing the email template in QuickBooks Desktop (QBDT).
You're correct in saying that you can customize your templates via the Insert Field drop-down menu. Be advised though, the options you see on the menu are the only ones you can insert on your custom template. With that said, Customer URL 1 isn't included on the list.
Take a look at this article for additional details on this process: Create custom email templates in QuickBooks Desktop. This includes screenshots for your reference.
In case you encounter any errors during this process, see this article for troubleshooting steps: Fix custom email template issues in QuickBooks Desktop.
Place a comment below if you have any other queries. I'll be sure to get back to you.
