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

2008-02-04 20:27:16
On Sat, 2 Feb 2008, Alessandro Vesely wrote:
Michael Deutschmann wrote:
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.

And it won't even matter most of the time.  The forwarder here is
confident that a bounce (whether internally generated after hitting a 5xx,
or relayed via SRS) will never be backscatter, so Forwarding Problem B is
not an issue.  The MAIL FROM is SPF-correct, so no Problem S, either.

That does leave Problem K, but fortunately Karma-counting domains aren't
very common.

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>

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

A mail domain that does not in-transaction reject when the mailbox
doesn't exist deserves to lose.  (They can wait until DATA if they want to
defeat stealth VRFYs.)

If there is an in-transaction rejection in Case 3/4, the forwarder will
have to shut down the input end of the forward anyway, to protect itself
from an accumulation of deadletters.  Procedures for this will already
need to be in place, to deal with users who fail to whitelist.  These
will have the effect of terminating the forward if the recipient cannot
be contacted.

---- Michael Deutschmann <michael(_at_)talamasca(_dot_)ocis(_dot_)net>

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