Yes, you go it right about the sent invoices, tony126.

Currently, we don't have an indicator that the sent estimate was already viewed by your client. We'll share this idea to our Product Development Team. They might consider this for future updates.

For now, we can only ensure that the estimate was received by your client. The Last Delivery indicator will appear below the Customer and the Email fields.

You might also consider using a third-party app to have an indicator that tells us that your client viewed the estimate.

Keep us posted if you need anything else. Have a great day!