Re: [dmarc-ietf] ARC-Seal is meaningless security theatre

["John Levine" <[e-mail]>]

In article <[e-mail]> you write:
>I thought long and hard about using a less inflammatory title, but I
>figure maybe going in hard is the right way here, because I'd rather
>fix this before it becomes a standard! (and thanks Dave for your
>thoughtful questions during the Prague DMARC session which prompted
>some of my thinking)

For the most part you're right, but there seem to be a few corner
cases that make it worthwhile.

Since it only makes sense to look at the ARC chain on mail that comes
from senders that are generally reliable, I've asked why you don't
just whitelist those senders and be done with it.  

The answer, at least at very large mail systems, is that a mailing
list sends nice clean mail, but then it starts forwarding lots of
spam.  I've seen this on some of the ICANN lists where someone got his
address book stolen that had both the lists and individuals'
addresses, so we're now getting mail through the lists with faked
addresses of a frequent participant.  ARC passes along info from
previous hops so the recipient can retroactively do filtering that the
mailing list didn't.

I personally don't expect to do that, but if Gmail says they will,
I presume they will.

R's,
John