Yakov Shafranovich <research(_at_)solidmatrix(_dot_)com> writes:
Graham Murray wrote:
Roy Badami <roy(_at_)gnomon(_dot_)org(_dot_)uk> writes:
The effect of this is that even if the users MUA is Sender ID aware,
and displays the PRA, there's no guarantee it is displaying the same
identity that was validated by the MTA.
Which is why it would be better for the MTA to create a header to
inform the MUA of the PRA and for the MUA to display that. If this
were done then it would be necessary to specify that the MTA MUST
remove any such headers already in the mail.
This would be a problem with multi-hop forwarders.
Why? Sender-ID only authenticates the last hop anyway, so the PRA
which the MUA would derive should always be the same as that derived
and validated by the last MTA handling the email.