The Bcc property returns the list of addresses that are to
receive blind carbon copies of the message. Setting the property
creates or modifies the Bcc header field. Multiple addresses can be
specified by separating them with commas.
A blind carbon copy is when a copy of a message is delivered to a
recipient, but that recipient is not listed in the message headers.
Because the other recipients of that same message will not see the
address in the headers, they will not know it was delivered to that
person. As a result, the Bcc header field is not normally exported
when the ExportMessage method is called, or when the contents
of the message are referenced using the Message property. To
include the Bcc header in the message, use the
mimeOptionAllHeaders option. Of course, if this option is
specified, the addresses in the Bcc list will no longer be blind to
the other recipients.