On Tue, 16 Feb 2016, John Levine wrote:
https://tools.ietf.org/html/draft-moore-email-addrquery-01
Unfortunately, the draft is useless for end-to-end encryption, as it
relies on a clean path from the client to the recipient's SMTP server ...
I would encourage anyone interested in this topic to read the draft,
particularly section 4. No, it does not depend on a clean path from
the MUA to the recipient MTA.
This section defines a service extension to the Mail Submission
Protocol [RFC6409] which can be used by an authenticated, authorized
client to query an SMTP server on port 25 for information about an
email address. This is intended only as a workaround for port 25
blocking, so the extension is minimally tailored for that purpose.
So if my ISP is blocking port 25, I am forced to ask my ISP if the
remote party could accept encrypted email and to which key?
It is not "end to end" encryption, if the ISP can change the outcome.
So again, the above draft does not provide a workable solution for
the openpgpkey draft.
Paul