Hi there, @DFB.

I appreciate you joining the thread and trying the possible fixes to resolve this issue. Allow me to chime in and help you route to our support.

Updating your QuickBooks Desktop to the latest release and performing the Verify Rebuild Tool should fix the issue of the inability to open customer letters in Word. Since none of them work, I recommend contacting one of our experts. They can pull up your account to check unforeseen conditions of your company file and perform a screen-sharing session for further isolation.

Here's how:

1. In your QBDT account, select the Help menu and choose QuickBooks Desktop Help.
2. Then, click Contact Us.
3. Enter a brief description of your issue and select Continue.
4. Log in to your Intuit account and click Continue. Then, select Continue with my account.
5. You'll receive a code. Enter it and select Continue.
6. Next, choose either Chat with us or Have us call you.

You can use this link as a reference to get their contact details: Contact the QuickBooks Desktop Customer Support Team.

I'm adding these articles that will guide you in personalizing your email templates in QuickBooks:

• Customizing forms and writing QuickBooks Letters
• Create custom email templates in QuickBooks Desktop

Let me know how the contact goes, or leave a comment below if you need anything else. I'll be right here whenever you need my help.