Good day, Angie3124.

QuickBooks Online (QBO) doesn't have a report that allows you to review the emails you've sent. Instead, you can turn on the  Email me a copy feature. This will let the system automatically send you a copy of the email that you've sent to your clients.

Let me guide you how:

1. Click the Gear icon in the upper right corner.
2. From the Your Company column, choose Account and Settings.
   
3. Select the Sales tab on the left.
4. In the Messages section, click the Edit icon (pencil image).
5. Put a check mark in the Email me a copy at [your email address] box.
   
6. Click Save and Done once you're through.

I recommend reading this article that will guide you in personalizing your form designs and adding the information that matters the most to your business: Customize invoices, estimates, and sales receipts in QuickBooks Online

In the meantime, I'd suggest visiting our QuickBooks Online Blog regularly. This way you'll be updated with the latest news and updates including product improvements. 

Get back to me if you have any other questions. I'm always here to help. Have a good day!