Hello, chowchowlover.

Thanks for reaching back out to the Community about sending emails from your QuickBooks Desktop (QBDT) account. I want to ensure that this gets taken care of for you.  

Since you've tried contacting our Customer Support Team and troubleshooting steps, I recommend consulting with your IT professional about this problem. They'll be able to further review your computer and acknowledge what's causing this to occur.  

In the end, if your issue is persisting, I suggest getting in touch with our Customer Support Team again. Once you've told them everything you've done to help resolve this problem, they'll try to help create an INV to deeply look over this situation.   

Once everything is okay, you're now ready to email forms. To learn more about this, see this resource: Email sales forms, invoices, and statements in QuickBooks Desktop.

Additionally, I'm also adding this article to view different details on how you can fix possible errors when you send emails in QuickBooks Desktop: How to fix "QuickBooks is unable to send the email since your antivirus has blocked outgoing emails".... 

Don't hesitate to tag my name in the comment section below if you have further concerns or questions when using QuickBooks. I'm always ready to help. Keep safe and have a good day.