On Mon, May 5, 2014 at 12:46 PM, Murray S. Kucherawy
<superuser(_at_)gmail(_dot_)com>wrote:
How? I'm fairly certain it does neither.
Sorry, I missed that there were later replies.
The SMTP state machine is not changed by DMARC any more than SPF or others
changed it. It doesn't add any new states, verbs, parameters, or anything
else. DMARC sits at least two "layers" above where SMTP operates. As with
any number of other filtering systems, it can influence SMTP's final DATA
reply, but that's hardly unique or even unusual.
There is no new protocol element introduced by DMARC to DNS either. There
are no resource record types registered, no new protocol elements added,
etc. No part of the deployed DNS infrastructure needs to change for DMARC
to work.
As Dave pointed out, it's a layer on top of other widely deployed things.
-MSK