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RE: [spf-discuss] Re: solving the forwarding problem

2005-09-14 17:36:48
From: Frank Ellermann [mailto:nobody(_at_)xyzzy(_dot_)claranet(_dot_)de]
Sent: Wednesday, September 14, 2005 6:37 PM


Seth Goodman wrote:

Troll alert, this thread went "bounces-to", take care
[...]
Troll response:

address to send notifications of delivery
problems == bounces-to

It's now more than a year that Tony pushed 1123 5.3.6
right into my open mouth.  Everybody else here probably
had his facts straight long before that time.  It's now
very unlikely to find any "new" argument for this troll.

As you can imagine, nobody likes being called a troll.  I'm not sure what
you're objecting to, but I'm quite familiar with that section of 1123 and
have been for a long time.  To save anybody else who is interested the
trouble of looking it up, here is the section in its entirety:


      5.3.6  Mailing Lists and Aliases

         An SMTP-capable host SHOULD support both the alias and the list
         form of address expansion for multiple delivery.  When a
         message is delivered or forwarded to each address of an
         expanded list form, the return address in the envelope
         ("MAIL FROM:") MUST be changed to be the address of a person
         who administers the list, but the message header MUST be left
         unchanged; in particular, the "From" field of the message is
         unaffected.

         DISCUSSION:
              An important mail facility is a mechanism for multi-
              destination delivery of a single message, by transforming
              or "expanding" a pseudo-mailbox address into a list of
              destination mailbox addresses.  When a message is sent to
              such a pseudo-mailbox (sometimes called an "exploder"),
              copies are forwarded or redistributed to each mailbox in
              the expanded list.  We classify such a pseudo-mailbox as
              an "alias" or a "list", depending upon the expansion
              rules:

              (a)  Alias

                   To expand an alias, the recipient mailer simply
                   replaces the pseudo-mailbox address in the envelope
                   with each of the expanded addresses in turn; the rest
                   of the envelope and the message body are left
                   unchanged.  The message is then delivered or
                   forwarded to each expanded address.

              (b)  List

                   A mailing list may be said to operate by
                   "redistribution" rather than by "forwarding".  To
                   expand a list, the recipient mailer replaces the
                   pseudo-mailbox address in the envelope with each of
                   the expanded addresses in turn. The return address in
                   the envelope is changed so that all error messages
                   generated by the final deliveries will be returned to
                   a list administrator, not to the message originator,
                   who generally has no control over the contents of the
                   list and will typically find error messages annoying.


This is pretty easy to interpret and has little to do with what I was
talking about.  Mailing lists change the return-path to a list account
(automated VERP bounce processor).  Forwarders change the RCPT TO and leave
MAIL FROM alone.  If you can show me how this is in any way in conflict with
what I have said in this thread, or what it even has to do with it, I would
surely like to know.



So if you have better ideas than SPF please submit them
mailto: internet-drafts AT ietf.org and let's discuss it
e.g. here after you have done this.

I did not suggest that SPF not be implemented.  I have often suggested that
SPF _does_ have a forwarding problem (surprise, surprise!) and have
suggested SES as one possible solution.  Even in that case, SES does not
replace SPF, so your comment does not make much sense.  Alex and I were not
discussing SES, though others mentioned it in two posts out of around sixty
in the thread.  Even if we were discussing SES, your admonition that I must
submit an I-D before talking about it here is inappropriate.

--

Seth Goodman

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