Re: Fastest way to inject a lot of mail?

John Levine  wrote:

(hint: "TUNING"...)

I did and unless I missed something, it says nothing about injecting

You are looking for an answer to one specific question - but maybe
your question does not address the actual problem?
As others have told you: if you don't know what's "slow", you won't
be able to solve the problem -- except maybe by trying different things.
So you could just try your alternative (one SMTP session, multiple
transactions) to see what happens.
PS: someone once complained that some MTA was slow sending mail
until I asked them about the actual data... which showed their
(outgoing) internet bandwidth was completely used by the MTA (because
they sent one RCPT per TA with "lots" of RCPTs and large mails).
That is, unless you know which bottleneck is actually "hit"
it's hard to tell what to do differently...
--
Note: please read the netiquette before posting. I will almost never
reply to top-postings which include a full copy of the previous
article(s) at the end because it's annoying, shows that the poster
is too lazy to trim his article, and it's wasting the time of all readers.