Learn how to use BCC in Outlook
Description: If you want to hide the names and addresses of recipients in an email, you can use Bcc, which stands for “blind carbon copy”. Here's how it works.
Open up Outlook and then open a new email.
When open go to the Options tab and from there you will see the Bcc field. By clicking on this it will add another layer to your email below the To and Cc fields as highlighted in the image below.
Now you can select who you want to Bcc that message to. The link below has takes you to a video of how to do this.
Link: https://support.office.com/en-us/article/The-ins-and-outs-of-BCC-39c17ac8-67cd-4412-8a82-c119a34c9de1?ui=en-US&rs=en-US&ad=US