Hi jodie8,
Are you referring to bounced or undelivered invoices from QuickBooks Online? If the delivery failure error is sent to us by your service provider, a notification is added to the transaction. You’ll have to click on the View the errors link on your Dashboard to see the lists of failed emails.
If you're not seeing the Dashboard message, you can check from within the invoice you sent to see if it was delivered or not, under the Customer's name.
If you don't get any message, then the email has reached the recipient, but if they don't receive it, they may have to mark [email address removed] as a safe sender.
Also, you can check this article about invoices not sent 3 solutions for you when customers aren't receiving your emails.
Feel free to reply to this post if you have further concerns. I'll be around to help you.
