Hello _Al_!
Thanks for joining us here. I understand that you need to edit the email template before sending the invoices. Allow me to help you.
If you're using Outlook, the edits and sending of emails are all happening in Outlook. That means QuickBooks Desktop does not have any control over it.
As a workaround, you'll want to set up and use webmail instead. Check this link and proceed to the Set up your secure webmail to work with QuickBooks section: Connect your email to QuickBooks Desktop.
In addition, I've added this article if you'll want to customize your sales forms: Use and customize form templates.
Leave a comment again here if you need more assistance. Take care!
