Hello there, @imhere2day.

I understand how convenient it is in sending invoices in QuickBooks Online (QBO). I’m here to share some details that can help you with the delivery errors you’ve encountered in QuickBooks Online.

As of the moment, there's an ongoing investigation into whether users are experiencing bounced emails when sending invoices. Rest assured, our engineering team is working on a fix. 

In the meantime, Also, I want to ensure you're in the loop about the investigation's status and its fix. With this, I recommend contacting our Customer Care Team. They can add your company to the notification list so you'll receive email updates.

Please ensure to check our available hours when contacting our support so we can address your concern on time. 

You may also want to consider manually downloading your invoices and sending them to your customers. 

Also, you might consider checking out this article here just in case you want to personalize your sales forms in QBO: Customize invoices, estimates, and sales receipts. 

Please bear with us as we're working on this. Keep me posted if you have any other questions or concerns about managing your invoices. The Community always has your back. Keep safe always.