We're unable to view the sent invoice's email body (that has been edited before sending to the customer). I'd recommend reaching out to your customer, and let them send the details of the email.
This would also be a good opportunity to improve the product. You can send your feedback to our Product Development Team. Feel free to click the Gear icon in the upper-right corner and select Send Feedback Online.
You might want to set up your QuickBooks so you can also receive the invoices you'll send to the customers in the future. Here's how to do it:
1. Click the Gear icon in the upper-right corner and select Account and Settings.
2. Select the Sales tab and go to the Messages section.
3. Make sure to mark the Email me a copy at (email address) box.
4. Or Cc the invoice to other email address.
5. Click Save and Done.
Please let me know if you need anything else. I'll be around.