Rolf E. Sonneveld wrote:
On 5/13/11 8:12 PM, Alessandro Vesely wrote:
[...]
"In such cases where the submission fails that test, the receiver or
verifier SHOULD discard the message but return an SMTP success code,
i.e. accept the message but drop it without delivery. An SMTP
rejection of such mail instead of the requested discard action
causes more harm than good."
I would remove the SHOULD as the argument (second sentence) is
clear. The usage of the SHOULD raises the question about whether
this is a SMTP receiver action and whether it is appropriate to
create a black hole (silent drop of message).
This should have been explained more clearly in RFC 5617. Perhaps, we
should say that "discardable" means "droppable" in general?
The problem what 'discardable' means has been introduced in RFC5617 and
I don't think draft-ietf-dkim-mailingslists-10.txt has to 'fix' that
problem.
Nothing wrong with DKIM=DISCARDABLE. What is wrong is trying to
dictate to others MLM should ignore ADSP.
As a MLM vendor, I have technical and ethical engineering obligation
not to cause problems when taking on a new inherently incompatible
technology that doesn't naturally fit with a MLM.
Hence, there are two general solutions for the MLM:
MLM-LEVINE: Ignore all DKIM ADSP restrictive policies
MLM-SANTOS: Preempt all DKIM ADSP restrictive policies
I know as a matter of fact MLM-SANTOS is a better DKIM mail
integration fit because we implemented it.
Also, you can't dictate to receivers they should ACCEPT and DROP.
Although that could be feasible solution to solve MLM ignorance to
support ADSP, its a very difficult issue when increasing receiver
practice is rejecting bad mail at the DATA level.
What I had proposed is is method (rule) at the DATA filter:
if message fails ADSP and has a LIST-ID,
then respond 250 and discard the message
if message fails ADSP and has no LIST-ID,
then reject with 55x
The problem is the MLM that is *ignoring* ADSP and passing on the buck
to ADSP ready member receivers adding the overhead to receivers and
also creating new MLM problems for itself. A repeated SMTP level
rejection will cause harm to list member by the MLM sender creating
false automated unsubscribing notifications when the attempts are
exhausted. So if the receivers can detect its a MLM sender incorrectly
sending ADSP protected mail, then the only recourse, in the name of
not causing problems and backing up the ignorant MLM, is to accept
(250) and then drop the message.
But the real solution is for the MLM to follow proper DKIM mail
integration considerations when adding something new it hasn't done in
40 years.
--
Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com
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