On Wed, 9 Feb 2011, Michael Deutschmann wrote:
On Tue, 8 Feb 2011, Stuart D. Gathman wrote:
Then maybe we should make it one. It is a simpler and easier alternative to
deploying SRS (although more trouble for the final receiver).
It would work better to promulgate Sham SRS, which would avoid the
scalability problem of your hack.
As a less clueless than average email sender, I would much prefer
having the email simply rejected by SPF fail to Sham SRS. The DSN
from the forwarder would contain the new email, and I would simply resend to
that. Sham SRS gives no notice of delivery problems (unless the forward
is the final hop). I realize the average email user never actually reads DSNs,
so this is not a general solution.
What if there was a standard SMTP code for SPF fail? Then a non-SRS forwarder
could easily send an end-user friendly DSN to facilitate resending
to the new email?
But this is a distraction from the question I originally pondered, which
is -- given a site that has whitelisted all its friendly incoming
forwards, yet is using a whitelisting heuristic that the forwarding
entities have not promised not to break, can it reject on an ordinary fail
when the whitelist engine says "not a trusted forward"?
I say "yes". But I also realize that this is a judgement that
others may disagree with (not a black and white issue). Keep in mind
that rejecting on SPF fail after alias forwarding is not such a horrible thing.
If the forwarder MTA is standards compliant, the user is notified of the new
address, and can resend. At least the email doesn't go in the bit bucket.
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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