You're unable to edit the email message to an existing invoice template, @KarenSanders.

You'll have to add a new template and make modifications so you can use it when sending invoices to your customers.

Here's how:

1. In your QuickBooks Desktop, go to the Edit menu, then select Preferences.
2. Click Send Forms and go to the Company Preferences tab.
3. Select Add Template.
4. In the Add Email Template window, enter the correct information and click Save.

Just in case you'll want to personalize your invoice, you can check out this article for the detailed steps and information: Use and customize form templates.

Please touch base with me here for all of your QuickBooks needs, I'm always happy to help. Have a great day.