It would be nice if it showed that an estimate has been sent to an email address or not like it does for invoices?

What kind of business do you run? You may have an additional app to integrate with your QBO account as a workaround.

Hi there,

Thanks for reaching out to us here. It's important to make sure that the estimate in question is received by your customer. QuickBooks offers a powerful feature that allows you to send estimates by email to your customers. I'll be glad to point you in the right direction so you can achieve your goals with ease. 

The estimates feature in QuickBooks allows you to view the email and the date when the estimate was sent. You can check this by opening the estimate in question and checking the estimate status on the top left corner just under Customer. For visual reference, feel free to check out the screenshot below.

Let me know if you need any further help, I'll be happy to assist.