A blind carbon copy is a copy of the mail
message that is sent to one or more recipients without the knowledge
of the primary recipients. Primary recipients are listed in the
To: and Cc: lines. When there
are multiple blind carbon copy recipients, knowledge of each other is
When run with a -t command-line switch (to gather
recipients from the headers), the sendmail
program achieves this end by saving a list of all the blind carbon
copy recipients, deleting the Bcc: header line,
and then delivering to each blind carbon copy recipient. (See the
The Bcc: header should never
be declared in the configuration file.
The field for the Bcc: header must contain one or
more properly formed addresses. Where there is more than one, each
should be separated from the others by commas.