Out of curiosity, what MTA's currently support SMTP pipelining,
and what percentage market share do they currently have in total?
Lotus Notes SMTP gateway, ISODE's PP, and MMDF do not as far as I know. (I
believe the latter two actually don't implement ESMTP of any sort.)
I also suspect that Exchange, NOTES, and PP are "pipeline clean"
but don't say so
I noted the reference to Isode's PP (we do still call it PP, but for
marketing purposes it goes under the title "Internet/X.400 Message Switch".)
You are correct that PP does not implement SMTP pipelining and that it
is "pipeline clean". I don't think we would claim pipelining unless
we made the servers take advantage of it (not a big deal to code, but
I can't see much benefit, although you would need it for this sort of
You are incorrect in your belief that PP does not implement ESMTP. We
have supported ESMTP for some long while and continue to add ESMTP
extensions. However, the current relase (not the release which is
about to ship) can be built with ESMTP turned off, so you will see
deployed systems which appear not to have ESMTP.