Murray S. Kucherawy wrote:
[mailto:ietf-dkim-bounces(_at_)mipassoc(_dot_)org] On Behalf Of Michael
Sent: Thursday, May 27, 2010 6:22 AM
To: Roland Turner
Cc: DKIM List
Subject: [ietf-dkim] bad mail blowback
So the question is, in my mind, should the receiver just silently discard
it which breaks reliability but allows the MLM to do nothing special, or
should the receiver bounce/5xx it back. To my mind, if the MLM is going to
do something as drastic kick the receiving user, it ought to at least be
open to a 5xx explanation that it's the mail in question that's the problem
instead of blindly giving the user X number of 5xx's before they're declared
a nuisance and kicked.
This is something the lists BCP could discuss. Perhaps something like:
bounces with enhanced status codes of 5.7.1 should not be counted against the
recipient as they are done for message-specific policy reasons and not for
something more general.
(I might have the "5.7.1" wrong, but you get the idea.)
There is apparent consensus that posting to MLMs using discardable
addresses is a bad practice. By discouraging it, the BCP already
implies that any ADSP/MLM conflicts are odd cases that someone has
to handle specifically. But who?
There are three actors involved: the domain who set "discardable",
the user who posts to MLM, and the MLM who breaks the domain's
signature. I think no advice can satisfy all them. However, I'd opt
for letting the domain admins know about the fact, since they chose
to reject rather than drop. That is,
MLM: in case of ADSP rejections, kick the user
unless you are sending a dkim-report to the admins.
Kicked users will report to the admins themselves, unless they
already know what to do. Notified admins can prepare alternative
addresses, whitelist, authorize, etcetera. List grandmas can avoid
bad experiences to their subscribers that way.
Of course, it would be even better, and smoother, if MLM rejected
the offending posts in the first place. /Participating/ MLMs do so.
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