Thank you for joining this thread, shortcut1. Currently, you can manually adjust the email message each time you send a payment receipt to your customers. However, the option to set a custom default message to minimize repetitive manual adjustments for each transaction is not available at the moment.
 

In the meantime, I recommend submitting feedback to our Product Development Team.  will consider your suggestion and implement changes to enhance your experience with QuickBooks Online.

Here’s how you can send feedback:

1. Go to the Gear icon.
2. Under the Profile column, select Feedback.
3. Enter your comments or product suggestions.
4. Select Next to submit.

To stay updated with product changes, check the Customer Feedback Updates page.

If you want to personalize your sales forms to match your business preferences better, you can refer to this article for detailed guidance:

Customize invoices, estimates, and sales receipts in QuickBooks Online.
 

Please don't hesitate to reply to this thread if you have further concerns when changing the email message in your payment receipt. I'm here to assist you further!