On Wed, 2001-09-26 at 01:50, Julian King wrote:
> > 2) EXIM can deliver all messages during a single SMTP session to the
> > same email system (useful for mass system like HOTMAIL,YAHOO, ....),
> > QMAIL no.
>
> Intuition to me would indicate that you are prepared to throw enough
> CPU at the problem to be able to saturate your link, thus anything which
> you can do which will reduce the amount of data sent is likely to be a
> winner.
>
> For that reason, if no other, I would suspect that exim's style of
> delivering messages down one pipe will win, if that is the only
> consideration.
The way the injection was described, you will not, in general, get *any*
multiple SMTP session use in this scenario.
SMTP sessions are only reused if there is hint information saying that a
message is waiting on that host. As these are going to be all first
deliveries, this won't happen.
You could do the queueing with the -odqs option, or with
"queue_smtp_domains = *" set. This will slow down the injection by
doing some of the DNS work at inject time, but would allow some reuse of
SMTP sessions at delivery time.
Not sure it will save much at all... and in any case what you will find
is that 90% of the stuff will be delivered in one pass, but the other
10% or so will stick around for one or more additional delivery
attempts.
Standard accellerators like the disk subsystem and having a decent local
DNS cache would be required.
This is an unusual configuration for any mail system. You are likely to
see some very odd results if you put qmail/exim/postfix head-to-head. I
would guess that the time to last successful delivery would be pretty
much the same for all of them, but that the graph of percentage
delivered against time, and the bandwidth in use would be somewhat
different (I would not like to predict the shape for any of them).
Nigel.
