module Mail
  grammar EnvelopeFrom

    include RFC2822

    #        The exact character sequence of "From";
    #
    #        a single Space character (0x20);
    #
    #        the email address of the message sender (as obtained from the
    #        message envelope or other authoritative source), conformant
    #        with the "addr-spec" syntax from RFC 2822;
    #
    #        a single Space character;
    #
    #        a timestamp indicating the UTC date and time when the message
    #        was originally received, conformant with the syntax of the
    #        traditional UNIX 'ctime' output sans timezone (note that the
    #        use of UTC precludes the need for a timezone indicator);
    #        Thu Nov 24 18:22:48 1986
    #
    #        an end-of-line marker.
    rule primary
      addr_spec ctime_date
    end
    
    rule ctime_date
      day_name " "+ month_name " "+ day " " time_of_day " " year
    end
    
  end
end