How to Bcc in Outlook
If you are the recipient of the message, you cannot see Bcc recipients added by the sender. In everything else, the Bcc field works like the To and Cc fields in Outlook, but you will not find it in the New Message window. To show the Bcc field in Outlook, do the following:
1. Open a new email message or reply to or forward a message.
2. In a new, a reply or forwarded message, on the Options tab, in the Show Fields group, click the Bcc button:

The Bcc field appears below the Cc field:

- In the Bcc field, type the recipient address or addresses you want to hide from other recipients.
- In the To field, type at least one address. It can be your address if you're going to send only blind message copies.
The Bcc field allows the sender to protect the privacy of the recipients. The regular To and Cc recipients cannot see Bcc recipients, and Bcc recipients cannot receive their replies to the original email. Bcc recipients see the To and Cc recipients and can reveal their personality unintentionally. If the Bcc recipient uses the Reply All command in Outlook, all other recipients automatically are added to the To and Cc fields and get the reply. Be prudent and do not use Bcc to share any personal or confidential communications!
Note: After pressing the Bcc button, all subsequent new, reply, or forwarded messages will contain the Bcc field. To hide this field, create a new message and click the Bcc button on the Options tab.
Outlook rules allow you to add a Cc recipient to emails you send automatically, but not Bcc recipients.
See also how to export all Contacts from Microsoft Exchange OST file storage to Microsoft Storage PST file.