Phillip,
HBP> I want to authenticate the purported originating email address
HBP> whether that be envelope or data FROM, Reply-To, Sender or
HBP> whatever.
Each of those contains a value with different semantics.
The key word in your sentence is "whatever". It is exactly that lack of
precision that will prevent reaching common, useful understanding and
consensus.
HBP> In terms of bare authentication alone the only link that seems
HBP> to me to add real value is authenticating the Data From: address.
I have not heard of a "Data From" address.
d/
--
Dave Crocker <dcrocker-at-brandenburg-dot-com>
Brandenburg InternetWorking <www.brandenburg.com>
Sunnyvale, CA USA <tel:+1.408.246.8253>