Back in February and March I drafted some SMTP extenstions that were intended to improve its performance and robustness. I’ve been revisiting this work recently because people from the IETF Lemonade working group have expressed interest in them.
Most of the work has been rewriting my REPLAY draft to make it closer to the checkpoint/restart extenstion specified in RFC 1845. I stripped out the excessive rationale sections, and described some of the protocol elements more carefully, and added a 1845 backwards compatibility mode.
However it looks like the Lemonade WG are more insteredred in QUICKSTART than in checkpoint/resume, so I’ve also made a few editorial updates to QUICKSTART, mostly updating references.