[Mailman-Developers] Sender field

[Barry A. Warsaw]

>>>>> "JCL" == J C Lawrence <claw@kanga.nu> writes:

    >> Anyway, back to my question, is Mailman doing this to conform
    >> with some rfc, or would it be safe to either remove the
    >> 'sender' header field og simply insert the "correct" 'from'
    >> address instead?

    JCL> I'm not aware of an RFC mandate which covers this area.  That
    JCL> said its worth realising that Sender is an unreliable header
    JCL> and may be re-written by the first MTA (depends on how the
    JCL> message was delivered).

RFC 822, section 4.4.2 says:

     4.4.2.  SENDER / RESENT-SENDER

        This field contains the authenticated identity  of  the  AGENT
        (person,  system  or  process)  that sends the message.  It is
        intended for use when the sender is not the author of the mes-
        sage,  or  to  indicate  who among a group of authors actually
        sent the message.  If the contents of the "Sender" field would
        be  completely  redundant  with  the  "From"  field,  then the
        "Sender" field need not be present and its use is  discouraged
        (though  still legal).  In particular, the "Sender" field MUST
        be present if it is NOT the same as the "From" Field.

        The Sender mailbox  specification  includes  a  word  sequence
        which  must correspond to a specific agent (i.e., a human user
        or a computer program) rather than a standard  address.   This
        indicates  the  expectation  that  the field will identify the
        single AGENT (person,  system,  or  process)  responsible  for
        sending  the mail and not simply include the name of a mailbox
        from which the mail was sent.  For example in the  case  of  a
        shared login name, the name, by itself, would not be adequate.
        The local-part address unit, which refers to  this  agent,  is
        expected to be a computer system term, and not (for example) a
        generalized person reference which can  be  used  outside  the
        network text message context.

     August 13, 1982              - 21 -                      RFC #822

     Standard for ARPA Internet Text Messages

        Since the critical function served by the  "Sender"  field  is
        identification  of  the agent responsible for sending mail and
        since computer programs cannot be held accountable  for  their
        behavior, it is strongly recommended that when a computer pro-
        gram generates a message, the HUMAN  who  is  responsible  for
        that program be referenced as part of the "Sender" field mail-
        box specification.

My interpretation of this section is that since regular deliveries use
the From: field supplied by the original author, but it is Mailman's
responsibility for sending the mail through the system, the Sender:
field ought to be the human responsible for list maintenance,
e.g. list-owner or list-admin.  It has proved to be more practical to
point Sender: at list-admin so that bounce processing can take first
crack at the message, sending it on to the list moderators if that
fails.

-Barry