Hector Santos wrote:
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.
Keep in mind that I recognize MLM-LEVINE solution but that is based on
ignoring all originating DKIM information - pass, fail or unknown.
The theory is based on:
A) The Member is already authorized based on being a list member
already, CONCUR
B) No expectation of getting fraud submissions, and if so, a
negligible amount, CONCUR
C) Ignorance for DKIM failure promoting a relaxed atmosphere of
DKIM unknown signer mail, OBJECT.
D) Trust the single signer domain at the SYSTEM LEVEL (global), OBJECT.
Assuming this MLM-LEVINE is the acceptable solution, then the
optimized, lower overhead receiver operation is to first check to see
if the signer(s) are known before even trying to verify any signature.
What I had proposed 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
Note, by fails ADSP, it is presumed the policy is DKIM=DISCARDABLE
To complete the logic for always accept systems:
if message fails ADSP then discard the message
You got to understand there is a split of how systems operate; many
systems for scalability reasons, especially in earlier days, always
accepted the message and then applies any mail filters. As hardware
and software (multi-threaded OSes) improved, and also to address the
bounce problem, more systems began to do more dynamic rejections at
the DATA level. The technical responsibility to issues bounces is
very strong. The idea of discarding was largely frown upon.
This multi-decade BOUNCE requirement mindset, which touches base with
1986 US EPCA provisions for avoid censorship claims, has changed for
the first time in RFC5321 with new semantics that recognizes the
contemporary needs to "drop mail" when reasonable non-frivolous new
considerations are appropriate. I pushed for this recognition known
new technology like Sender-ID and ADSP was on the horizon.
In short, Levine did a good thing by technically "legalizing"
discarding of mail.
--
Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com
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