On Tue, 20 May 2008, ned+ietf-smtp(_at_)mrochek(_dot_)com wrote:
There are likely to be cases within a domain where a client wants to get
his address "signed" with BATV but where you don't want to hand out the
shared secret (or private key for that matter) to the client. As such, a
missing component here is a on-wire way to ask some agent to form this
signing operation. The obvious place to have this is as an SMTP eubmit
extension, although of course other approaches are possible.
The usual approach would be to make this implicit by configuring the
client to use a submission server that adds the tag. I'm not sure why
you'd need or want any explicit signalling.
That assumes that the only time such an address is needed the goal is always to
immediately submit the message for transport using the submission server
operated by client's administrative domain. That may not be what I want to do
with the message. Just as one example, the client could be remote and could be
constained to submit mail to some other server.
Ned