Good morning, @stephan_desmoulin. 

Thanks for chiming in on this thread. It's great to see a new face around here. Allow me to share some information about the email delivery issue with invoices in your QuickBooks Online account. 

I reviewed the current investigation (INV-58793) and it's still in progress at this moment. We've raised this with the engineers and we'll be in touch with an update as soon as possible. They are working hard to get this resolved for everyone. 

To ensure that you get an update about the problem, contact our Customer Support Team to be added to a list of affected users. Just follow the steps my colleague gave above or the link that was just given. Make sure they know the investigation number when you speak with them. 

Please let me know how it goes. It's my priority that you're able to get back to running your business. I'm only a post away if you need me. Have a splendid day!