Create a new email message or reply to or forward an existing message. If the message you're composing opens in a new window, select Options > Bcc. If the message you're composing opens in the Reading Pane, select Bcc from the ribbon. In the Bcc box, add recipients, compose the message, and choose Send when done.
What do CC and BCC mean? CC stands for carbon copy—basically, sending a “carbon copy” of your message to the email addresses you have added to the field. BCC stands for blind carbon copy, allowing you to send a “carbon copy” of your message while keeping the email addresses you have added private.