Can I see on my invoices where I have emailed the invoice and where my customer opened the invoice?

In Quickbooks Online, when you are looking at the invoice on your pc, there are 4 tabs along the upper left. Click on the last one, Payor View, and then over to the right there is a drop down for status, which will show you view status. As for the actual email you sent it to, I have never seen anywhere that you can read that info, but what I would do is set up your invoice sending settings so that you always send yourself a copy when you send the original invoice to your customer. That way, you can go back and look at your copy and it will show the email addresses it was sent to up on cc: line.

I've got some information and alternative steps to help you,, @wwalkwe.

A tab that lists your emailed invoices is unavailable in QuickBooks Online (QBO). However, you can check if the invoices were sent or not  or even viewed or not by reviewing each invoice. Here's how:

1. At the left navigation panel, select Sales.
   
2. Click Invoices.
   
3. Click the Customer name.
4. Select Invoice activity.
   
   5. You can check if your customer viewed your invoice.
   

When a customer pays on their invoice, you can receive and record the payments to track your account balance.

You can always hit the Reply button if you have any additional questions regarding your invoice. I'll be around to lend a hand. Stay safe!