1. Go to the Invoices page, and find the invoice you want to check the email delivery for.
2. Hover over the invoice to see the additional menu on the right-hand side.
3. Click on "Sending Status", and you will be able to see if the invoice email was sent successfully.
Note: Due to the nature of email and the partners we work with in order to provide the best email deliverability, there is a delay of 10-60 minutes for the status. This means that an invoice might show as "sent" but later changes its status to "error". We recommend checking the sending status about one hour after actually sending it.