Pleasure to see you here, @jan-heartlandfir.
Let me share the difference between bounced and undeliverable emails.
When we say bounced emails, it means that the server rejected them. On the other hand, Undeliverable occurs when the email server is unavailable. In both cases, your client didn't receive the email you sent them.
For further insights about the two, I've collected articles you can check out below. It contains steps to see the list of bounced emails with delivery errors and how to resolve undelivered invoices:
In case your customers aren't getting your invoices, reports, or other sales forms via email, you can utilize this write-up to resolve this: Troubleshoot if customers aren't receiving emails from QuickBooks Online.
Reach out to me again if you have additional queries about bounced emails and undeliverable. I'll make sure to answer them all. Have a pleasant day!
