Let me share additional information about this concern, @Tony-Z.
The on-going investigation about QuickBooks' unexpected behavior when sending your emails using Outlook is still open. It will remain its status until a permanent resolution is being released.
Currently, we don't have a specific estimated time frame on when this will completely be fixed. In the meantime, you can follow the workaround shared by my colleagues in this thread. Lastly, You can set up and use webmail in sending your emails in QuickBooks.
Rest assured, once there are developments on this on-going investigation it will be released as an update. Just make sure to enable automatic updates in your QuickBooks software.
Also, you'd received an email notification about it. That being said, I'd recommend contacting our Technical Support Team so you'd be included in the affected users' list. Just provide this investigation number - INV 0671 together with your name and updated email address.
Don't hesitate to share with us how your call goes. I'm always here to help.