Re: Default mail address

[Per Abrahamsen <abraham@dina.kvl.dk>]

joda@pdc.kth.se (Johan Danielsson) writes:

> What is so good about adding a useless `address' as sender of the
> message?

For News, Son-of-RFC 1036 compliance:

          6.4. Sender

          The Sender header identifies the poster, in the  event  that
          this differs from the author identified in the From header:

               Sender-content = From-content

          In  the  absence of Sender, the default poster is the author
          (named in the From header).

               NOTE: The intent is that the Sender header have  a
               fairly  high probability of identifying the person
               who really posted the  article.   The  ability  to
               specify  a  From  header naming someone other than
               the poster is useful but can be abused.

          If the poster supplies a From header, the posting agent MUST
          ensure that a Sender header is present, unless it can verify
          that the mailing address in the From header is a valid mail-
          ing address for the poster.  A poster-supplied Sender header
          MAY be used, if its mailing address is  verifiably  a  valid
          mailing  address for the poster; otherwise the posting agent
          MUST supply a Sender header and delete (or rename,  e.g.  to
          X-Unverifiable-Sender) any poster-supplied Sender header.

               NOTE:  It  might  be  useful to preserve a poster-
               supplied Sender header so that the poster can sup-
               ply  the full-name part of the content.  The mail-
               ing address, however, must be right.   Hence,  the
               posting  agent  must generate the Sender header if
               it is unable to verify the mailing  address  of  a
               poster-supplied one.

               NOTE:  NNTP implementors, in particular, are urged
               to note this requirement  (which  would  eliminate
               the  need  for  ad  hoc headers like NNTP-Posting-
               Host), although there are admittedly  some  imple-
               mentation  difficulties.   A user name from an RFC
               1413 server and a host name from an  inverse  map-
               ping  of  the  address, perhaps with a "full name"
               comment noting  the  origin  of  the  information,
               would be at least a first approximation:

                    Sender: fred@zoo.toronto.edu (RFC-1413@reverse-lookup; not verified)

               While  this does not completely meet the specs, it
               comes a lot closer than not having a Sender header
               at all.  Even just supplying a placeholder for the
               user name:

                    Sender: somebody@zoo.toronto.edu (user name unknown)

               would be better than nothing.

Gnus should not create Sender for mail.