That doesn't mean that an ARC signature chain is a bad idea. I have doubts about its effectiveness in practice, but, if it help, that is great. But changing the intuitive (and business-letter-based) semantics of the "From:" field strikes me as a bad idea ...
It strikes pretty much everyone as a bad idea other than a handful who've drunk too much DMARC koolaid, a group that does *not* include the ARC authors.
The whole point of ARC is that lists do whatever they do now, and add ARC headers for automated parocessing like they added DKIM headers a few years back. None of the headers visible to users are supposed to change.
Regards, John Levine, johnl@xxxxxxxxx, Taughannock Networks, Trumansburg NY Please consider the environment before reading this e-mail.