Hi there, @shueck.

When you have added the two Outlook accounts in QuickBooks, make sure that you have chosen the business account as your default.

For example, you've added both accounts in Outlook, personal and business, there's an option there to set it as default. I've added a screenshot as a reference.

1. Click the Edit menu and choose Preferences.
2. Click Send forms.
3. Go to the My Preferences tab 
4. When you've already added both Outlook emails, set the business account as default (Set as Default).
5. Then select OK.

Also, your Outlook emailing service may use the personal account, you may need to change the account used to send email messages in Outlook's Account Settings and set your business account as the default one.

If the issue persists, I recommend contacting our Tech Support Team to investigate this further. From there, they can pull up your account to check what causes this hurdle and give you additional fixes.

Here's how to reach them:

1. Click the Help menu at the top, and then select QuickBooks Desktop Help. 
2. Hit Contact Us.
3. Enter a brief description of your issue, for example, Invoices send from the same (often incorrect) email address in QuickBooks. 
4. Hit Let's talk. 
5. Choose Start a chat or Get a call.

Please share with us how it goes with my fix or the fix provided with our chat or phone tech teams. I'll keep my notifications open. Take care, shueck.