Thanks for reaching the Community space, @Jersey.

I appreciate you for sending a screenshot of your concern. To fix this, let's make sure to update your QBDT with the latest release. Updating the software so you always have the latest features and fixes. I'll show you how:

1. In QuickBooks, click Help at the top. 
2. Select Update QuickBooks, then choose Update Now. 
3. Hit Reset Update and click Get Updates. 
4. When the download finishes, restart QuickBooks. 
5. When prompted, accept the option to install the new release.  

Once done, run the QuickBooks PDF & Print Repair Tool on the affected computers. This fixes issues with emailing a PDF form.

Here's how:

1. Close QuickBooks.
2. Download the QuickBooks Tool Hub file, then save it.
3. Open the file you just downloaded (QuickBooksToolHub.exe).
4. Follow the steps to install, then agree with the terms and conditions.
5. After installing, double-click the icon on the Desktop to open the tool hub.

Then, run the QuickBooks PDF & Print Repair Tool. Here's how:

1. In the QuickBooks Tools Hub, click Program Problems.
2. Select the QuickBooks PDF & Print Repair Tool. It will take about a minute to run.

After performing the steps, try to send invoices and estimates again.

You can follow the remaining process in this article: Troubleshoot PDF and Print problems with QuickBooks Desktop.

I've included these articles to know more about how to customize email templates and use them to send messages from QuickBooks:

• Customize email templates in QuickBooks.
• Use and customize form templates

You can always get back to me if you have any other questions about QuickBooks. I'm here to answer it for you. Have a great day!