Re: DMARC?

On Tue, 21 Aug 2012, Ian Eiloart wrote:
> Well, I think we need to lobby the mail client developers to show the
> email address, since it's critical. Heck, some don't even show the email
> address when you reply to the email. It's terrifying!
>
> But, the real responsibility lies with those who (should) have
> competence - the MTA operator.

The only thing the MTA could do is rewrite the From: to omit any display
names.  But that's problematic, since the DKIM signature requires that
From: be preserved byte for byte.  The MUA would be unable to verify the
signature, and just have to trust that the MTA checked it before mangling
the From:.

> And, if mailing lists break DKIM, that doesn't much matter - it's the
> list's reputation that recipients should care about. They need to add
> their own DKIM signatures.

They often do, but it doesn't help against ADSP or DMARC because the
mailing list does not own the private key needed to make a new signature
corresponding to the From:.

If ADSP/DMARC were sane like SPF, and declared a signature corresponding
to the Return-path: to be adequate, then this would work fine.

---- Michael Deutschmann <[email protected]>