[TUHS] Excessive bouncing ... argh!

Theodore Ts'o tytso at mit.edu
Sun Sep 24 00:07:25 AEST 2017


On Fri, Sep 22, 2017 at 01:51:43PM -0600, Grant Taylor wrote:
> I also feel like mailing lists are their own entity, and as such, messages
> should be from them.  Similarly, I think replies should be directed back to
> the list.  I think this is especially true for discussion type mailing
> lists.  Thus, I would be inclined to set from_is_list to munge also.

Unfortunately, munging the From field, while it does solve the DMARC
problem, has a very significant negative UI effect.  It means that
when you look at a summary of messages in a threaded summary, they
will all look like they came from the THUS mailing list, as opposed to
from the author of the posting.

This is actually the whole *point* of DMARC.  They want to make sure
that if you see a from field of paypal.com, it means "paypal.com", and
did not come from SCAMMER at MAKE.MONEY.FAST.NG.  So this is why DMARC
apologists who argue that this could be fixed by having MUA's hacked
so they display the X-List-From: field in the threaded mail summary
are wrong.  If you do this, then Nigerian spammers will be able to use
X-List-From: field to fool stupid e-mail users, and then Yahoo and
Paypal will end up pushing DMARCv2 (outside the IETF standards
structures, just as DMARC is pushed outside of the standards bodies,
but by big companies imposing their will on the rest of the Internet)
to censor the X-List-From: field just as DMARC is trying to force
mailing list reflectors to munge the From field.

	     		   	     	  - Ted



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