Thank you for clarifying the situation, @PBJ10. I completely see how this detail is important, especially when you're following up with customers to ensure they receive their invoices, @abrackin. Let me help provide as much clarity as I can here.

To view a detailed list of emails with delivery issues, let's navigate to the Tasks section in QuickBooks Online (QBO). On this page, you’ll see all the relevant details, such as the delivery date, transaction type, Ref No., customer’s name, error messages, and delivery method.

1. Go to Tasks.
2. Select the View the errors link.

If the Tasks page doesn't show the email associated with the undeliverable invoices, I recommend contacting our Live Support team. They can take a closer look at your account and ensure your customer receive their invoices.

1. In your QBO account, click the Help icon.
2. Select Search, then Contact Us.
3. Enter your question in the field, then Continue.
4. Choose either Chat or Callback for assistance.

In the meantime, we can manually review the affected invoices by navigating to the Sales Transactions page and filtering the Type to Invoices and status to Delivery Error. Then, customize the view by clicking the mini gear icon and enabling the Email. This will display a list of invoices marked as undeliverable along with their corresponding recipients. If you find any issues, you can edit the customer’s email address and resend the invoice.

I hope these steps help you better understand how to manage delivery errors and locate the affected email addresses. I know how important it is to ensure your customers receive their invoices on time, and I'm here to help if you have further questions. Take care.