[Resend latest version to hopefully get some "rough consensus" via
a simple "vote"]
* Client initiates by sending MAIL with an extension.
* RCPT returns normal reply codes (no 3yz)
* DATA and the last BDAT return (in order):
1. 353 to indicate the start of server responses
1.a. possible optimization: a single {2,4,5}yz reply code
to indicate the overall transaction status in
which case the next two steps are skipped.
2. one reply code per recipient which got a 2yz reply.
3. one end of mail reply code (as in the current ESMTP model,
which is the same as the "final" reply code in
draft-hall-deferrals).
So we still have to decide between:
(I) get rid of step 1.: 353 (and increase the timeout to the
first deferred RCPT response),
(II) or use 353 with the optimization 1.a.
Here's my vote: (II).