You can let your client modify their settings preference in QBDT, and there's nothing to change in your computer settings, @MJN. Below, I'll provide insights into the possible causes of this error and suggest steps you can take to resolve it effectively.

To begin with, could you please tell me if your client encountered any error messages or what your client is trying to do? This way, I can provide an accurate resolution to your concern.

In the meantime, I'll provide troubleshooting steps If you're client is referring to an issue where QuickBooks is unable to send emails to Outlook due to a setting issue. Here's how:

Step 1: Edit your admin privileges and make sure QuickBooks isn't set to automatically run as an administrator.

1. Close QBDT.
2. Open the Windows Start menu.
3. Type QuickBooks into the search. Then right-click the QuickBooks icon and select Open file location.
4. In the folder, right-click the QuickBooks.exe file and select Properties.
5. Go to the Compatibility tab.
6. Choose to 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.
7. Select Apply and then OK.

Step 2: Edit your email preferences in QuickBooks

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. Select Outlook as your email option and then OK.

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

1. Select the Edit menu and then Preferences.
2. Select Send Forms. Then go to the My Preferences tab.
3. Select 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 troubleshooting steps, you can check this resource: How to fix "Error: QuickBooks is unable to send your email to Outlook"

However, If your client is referring to the setup on your Outlook in QuickBooks Desktop (QBDT) to send invoices, reports, and more. Here's how:

Step 1: Contact your internet or email provider to get the following info

• Username and Password
• Incoming email server address and Incoming email server type
• Outgoing email server address

Step 2: Set up Outlook

1. Go to the QuickBooks Edit menu.
2. Select Preferences and Send Forms.
3. Select Outlook and OK.

For more detailed information on setting up Outlook to work with QuickBooks, refer to this guide: Connect your email to QBDT.

Additionally, you might want to check this article to learn more about repairing your QBDT file for data issues or if you suspect data damage: Fix data damage on your QBDT company file.

If you have any further concerns regarding the new Outlook issue, feel free to tag me in the comment section, and I'll assist you in any way possible.