In Outlook you can show, hide, and view the Bcc (blind carbon copy) box in an email message. Only the sender of a message sees the names of people (recipients) in the Bcc box. But everyone can see recipients in the To and Ccboxes. Anyone added to the Bcc box receives a copy of the message.
Turn on Bcc
After you turn on the Bcc box, it appears every time you create a message until it's turned off.
- Create a new email message, choose Options tab, and in the Show Fields group, choose Bcc.
- In the Bcc box, add recipients, compose the message, and choose Send when done.
Turn off Bcc
You can turn off the Bcc box for future messages at any time.
- Create a new email message, choose Options >Bcc.
NOTE: The background color distinguishes between the Bcc button being turned on or turned off. A dark background means the button is turned on, and a light background means it's turned off.
View Bcc recipient
If you're the recipient of a message and want to see if the sender added Bcc recipients, you can't. Only the sender of a message can see the names of Bcc recipients by opening a message in the Sent Items folder where all sent messages are stored by default.
- In the Sent Items folder, open the message you sent.
- In the Reading Pane, view the header section of the message.
TIPS: A + symbol indicates there are more recipients. In the screenshot, for example, +11 signals there are 11 more recipients listed in the Bcc box.Choose
to expand (open) your the message header section. And choose 
to collapse (close) the header section.
