You can see when your invoice has not been delivered to your customer.
By looking at the email status in the All Sales List or the Invoices List inside of QBO you will see the Undelivered status for invoices that have failed to deliver. Undelivered emails are accessible using the Needs Attention filter available in the money bar.
When you find that an invoice has not been delivered, please verify that the email address that you have for the customer is correct, edit if needed and try and send again. If the invoice was sent to multiple recipients we are unable to specify which one failed at this time. This means if the invoice was undeliverable for 1 of 3 recipients the status will say Undeliverable.
For bounced emails there are two main reasons that it wasn’t sent:
For dropped invoices: