Do you mind sharing what worked? I can't see your message before, just that it worked. This is an ongoing problem for me. Thank you in advance! 

Hello, any updates on this? issue with regards to this is still ongoing for us.

We're glad you've considered us here in the Community to help you, mianpor. I'll ensure you reach the appropriate support to help overcome the issue you encounter with Outlook.

Beforehand, have you already performed the troubleshooting steps outlined above? Updating your QuickBooks Desktop and Outlook to the latest release, repairing data integrity issues through the QuickBooks Tool Hub, and updating your settings and preferences can help isolate errors that prevent you from sending invoices seamlessly.

If the issue persists, I recommend contacting our customer support team to report these issues. With their tools and expertise, they can thoroughly examine the root cause of this matter to provide the most relevant fix and workaround. They can also raise a ticket for investigation if necessary.

Here's how:

1. Open your QuickBooks.
2. Proceed to the Help menu.
3. Select QuickBooks Desktop Help/Contact Us.
4. Click on the Contact Us tab.
5. Enter a brief description of your concern, then Continue.
6. Use your Intuit account to sign in or Create a new account, then Continue.
7. Enter the single-use code sent to your email and select Continue.
8. Either choose to chat with us or Have us call you.

Also, please observe their support hours so you can get immediate help.

On the other hand, ensure to record customer payments so that these amounts will be linked to their corresponding invoices. This practice helps maintain a balanced account for accurate reporting.

Please add a comment in this thread for questions or clarifications about sending invoices via email in QuickBooks Desktop. We're always willing to assist you in carrying out different accounting tasks.