If you add a recipient's name to the blind carbon copy Bcc box in an email message, a copy of the message is sent to the recipient. The recipient's name isn’t visible to the other recipients of the message (names entered in the To or Cc boxes).
Tip: If the Bcc box doesn’t appear, for instructions on how to display it, see Prevent recipient names from showing by using Bcc.
View all Bcc recipients of a message I received
The only person who can see the names of Bcc recipients of a message is the sender.
View all Bcc recipient of a message I sent
If you are the message sender, do the following:
Open the message that was sent. By default, sent messages are saved in the Sent Items folder. All recipients appear in the header section of the message.
Note: Bcc recipient names don’t appear when you preview messages in the Reading Pane. Only recipients on the To and Cc lines appear.