It isn't the experience we want you to have when emailing invoice to Outlook in QuickBooks Desktop (QBDT), TStone03.

Before we proceed, could you please confirm if the error message you’re seeing is exactly “QuickBooks is unable to send your email to Outlook.” or if it’s a different message? This will help us provide a more targeted solution.

If this is the error you’re encountering, we can perform these troubleshooting steps to help resolve the error when emailing invoices to Outlook:

First, ensure that QuickBooks isn't set to Run as an Administrator automatically. Here's how:

1. Close QuickBooks Desktop.
2. Right-click the QuickBooks icon, and select Open file location.
3. In the folder, right-click the QuickBooks.exe file and select Properties.
4. Go to the Compatibility tab.
5. Uncheck the Run this program as Administrator option. If the option is grayed out, select Show Settings for All Users. This makes the option available.
6. Click Apply and OK.
7. Restart QuickBooks and send the email again.

You can also edit your email preferences in your QuickBooks Desktop.

Here's how to do it:

1. In QuickBooks, select Edit and then Preferences. If you use Microsoft Outlook with Microsoft Exchange Server, open and sign in to Outlook before you move on.
2. Select Send Forms. Then go to My Preferences.
3. Choose Outlook as your email option and then OK.

Send a sample email from QuickBooks. If you still see an error, toggle your preferences.

1. Click the Edit menu and then Preferences.
2. Select Send Forms. Then go to the My Preferences tab.
3. Choose QuickBooks E-mail or Webmail, and then OK. This toggles your preference off.
4. Repeat the steps. Go back to the My Preferences tab and select Outlook. Then select OK.
5. Close QuickBooks and all other open programs.
6. Restart your computer.

For more detailed troubleshooting, please refer to this article:  How to fix "Error: QuickBooks is unable to send your email to Outlook".

Lastly, check out this article if you want to sync your QuickBooks customers, jobs, and vendors with your Outlook contacts: Sync Outlook contacts with QuickBooks Desktop.

Please keep in touch if you need further assistance with emailing invoices to Outlook in QuickBooks Desktop. We're here to help!