Hi @Melbu8,
Thank you for posting here in the Community. I have some information regarding the error when sending an invoice via Outlook in QuickBooks Desktop.
We've recently received reports from other users experiencing the same behavior when sending transactions via Outlook. At this moment, there's no specific timeframe for the complete fix.
Rest assured, our product engineers are doing their best to fix and prevent this from happening again. I'd suggest contacting our Customer Care Team again to verify if your company is already on the list of affected users.
Our team will send out notification emails once we have an update about the issue. This ensures you're in the loop about the status and its fix.
Our Customer Support Team for Pro, Premier, Plus is available from 6 AM - 6 PM PT (Monday - Friday). For Enterprise, any time, any day. See the steps to get a hold of a specialist:
- Open QuickBooks Desktop.
- Click the Help tab at the top menu bar.
- Select QuickBooks Desktop Help.

- Enter your concern, then hit Continue.
- Choose Get a callback.

For additional reference, I've attached a link you can visit to know more about sending forms by batch in QuickBooks: Email sales forms, invoices, and statements in QuickBooks Desktop.
Drop me a comment below if there's anything else I can help you with related to emailing transactions in Desktop. Take care.