spf-discuss
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Re: [spf-discuss] TENBOX/E (now SWK-SPF) rough draft

2008-02-02 08:06:38
Michael Deutschmann wrote:
So, for <sarah(_at_)example(_dot_)com> sending to <fred(_at_)example(_dot_)org> 
which forwards
to <ralph(_at_)example(_dot_)net>, example.org would do one of the following:

Case 1: Sarah's message got SPF pass, example.net offers SWK-SPF:
  MAIL FROM: <sarah%example(_dot_)com+HASH(_at_)example(_dot_)org> 
AUTH=fred(_at_)example(_dot_)org

This is where the solution works, and the "forwarding-from" address is made known to the recipient.

Case 2: Sarah's message got SPF pass, example.net doesn't do SWK-SPF:
  MAIL FROM: <sarah%example(_dot_)com+HASH(_at_)example(_dot_)org>

That's ok, if the recipient won't cooperate there's not much more we can do.

Case 3: Sarah's message got SPF neutral, example.net offers SWK-SPF:
  MAIL FROM: <> AUTH=fred(_at_)example(_dot_)org

Case 4: Sarah's message got SPF neutral, example.net doesn't do SWK-SPF:
  MAIL FROM: <shamsrs-fred(_at_)example(_dot_)org>
(where shamsrs-fred(_at_)example(_dot_)org 5xxes everything.  To circumvent 
dippy
admins who use callbacks, it might give 2xx at RCPT TO:, and save the 5xx
for DATA.)

In the latter two cases, a bounce may be needed to learn that a recipient mailbox has been deleted. It is pretty useless to keep an obsolete recipe which forwards to an inexistent address. For case 4, shamsrs-fred [at] example.org should reach the postmaster there, and he should do a manual check, deciding if the recipe should be deleted and if it is worth forwarding back the DSN to the original sender. (The Return-Path for manually configured recipes should reach the mailbox of the person who manually configured them.)

In general, I think an acceptable degree of RFC compliance -not just formal compatibility- is required for a protocol to became widely adopted.

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