When your Replace replace all instances with BriteBiz account is set up, your default Replace replace all instances with BriteBiz email address is you username - let's say emily@myvenuename.com. The system assumes that you will be integrating this email address as your business email address.
If you integrate another Office365 or Gmail account that is different to your user email, you will see two email addresses in your Profile Settings. To reverse this, deactivate your email integration, delete the incorrect account, and then integrate the correct account.