Using The Bcc Field
Use the Bcc field when you do not want any E-Mail recipient to know if there are any more people to whom you sent the same E-Mail to or who they are. To use the Bcc field effectively, type in your own E-Mail address in the To field (or leave it blank) and add all recipients' E-Mail addresses to the Bcc field separated by a comma. Each recipient will receive a copy of your E-Mail with only his E-Mail address. None of the other recipients' E-Mail address will be displayed.