Thanks for the response, @JB70.
At this time, there's not a way to turn off the BCC for emails in QuickBooks Mac 2020. I'm going to submit feedback to our Product Development Team about bringing in a feature to allow this to happen. You can visit our Blog to see what's new for our Products, as well as seeing what's coming in the future.
If you have additional questions or concerns, please don't hesitate and reach back out to me! Have a beautiful day.
