Thanks foe getting back to us, @shueck.

To help determine why invoices were not sending from your business account's Outlook email, I suggest contacting our Customer Care Team. They'll be able to run a remote-viewing section and identify the root cause of this issue since the business email was the default email on Outlook already.

Here's how you can reach them:

1. Click on Help at the top menu bar.
2. Hit on QuickBooks Desktop Help. 
3. Press on QuickBooks support. 
4. Select your preferred way to reach our support.

Keep me posted on how it goes, @shueck. I'll be around to help if there's anything else you need. Take care!