rfc1036 December 1987

3.  Control Messages

    This section lists the control messages currently defined.  The body
    of the "Control" header line is the control message.  Messages are a
    sequence of zero or more words, separated by white space (blanks or
    tabs).  The first word is the name of the control message, remaining
    words are parameters to the message.  The remainder of the header
    and the body of the message are also potential parameters; for
    example, the "From" line might suggest an address to which a
    response is to be mailed.

    Implementors and administrators may choose to allow control messages
    to be carried out automatically, or to queue them for annual
    processing.  However, manually processed messages should be dealt
    with promptly.

    Failed control messages should NOT be mailed to the originator of
    the message, but to the local "usenet" account.