BCC

Blind Carbon Copy, abbreviated BCC, and sometimes referred to as Blind Courtesy Copy refers to the practice of sending a message to multiple recipients in such a way that what they receive does not contain the complete list of recipients. Popularly used in the newsgroup group world, it allows users to send messages to a list of recipients that are blind to any intercepted readers of the message. Since usenet is global and generally does not restrict access to the messages of a particular newsgroup, the BCC functionality works as a security measure to assure that the addresses to those that the messages are intended for are not compromised.