"Alan DeKok" replied:
It's not the MAIL FROM which is flawed, it's the ability of the
recipient to believe the senders trust in the shared MTA, as anything
other than a statement of faith made by the vender.
Ah! Now here we can agree. We may differ as to _whose_ trust is broken, but the
crucial point is that a shared MTA is being trusted to have ensured that the
sender is authorised to use the Mail-From. There is no indication in the SMTP
protocol, or in the message headers, that this authorisation is actually taking
place.
I raised this problem as a criticism of PRA - where the MUA had no indication
that the MTA had actually verified the PRA.
Exactly the same criticism can now be directed at the current set of drafts.
All sorts of operational errors, changes in policy, etc., could mean that the
tests at the shared MTA have temporarilly ceased, yet the node is still being
trusted.
This should be of particular concern to those senders who use a shared outbound
MTA not under their administrative control (e.g. customers of most ISPs).
I've just posted a new thread "Proposal for VERIFIED keyword".
Would something like this help your trust concerns? It would mine.
Chris Haynes