Introduction
Enable Bcc via email settings. Create a new email message and add recipients to the Bcc field.
Instructions
1) Sign in to Outlook on the web.
2) Navigate to settings, and click View all Outlook settings.
3) Under Mail, click the Compose and reply tab.
4) Under "Message format", check the box next to "Always show Bcc" and click Save.
5) Click New message.
6) In the Bcc field, type the email addresses that you want hidden.
OUTCOME
The email addresses in the Bcc field are hidden to recipients when this email message is sent.