Hi jan-heartlandfir,

Thanks for posting in the Community!

In QuickBooks Online you can run an Invoice List to see the emailed invoice to a customer. Here's how:

1. Click on the Reports tab.
2. On the search box type in Invoice List.
3. Filter the Report period.
4. Click on Customise, and click on Rows/Columns.
5. Tick box for Sent.
6. Click on Run report.

You'll be able to see invoices sent to your customers. Alternatively you can also go to the Sales tab, and click Invoices under Status column you will see if an invoice was sent, paid or is overdue.

You can also check this link to learn more about: Create invoices in QuickBooks Online.

Please let me know if you have any additional questions with invoicing. I'm always willing to assist.