[Exim] Queue the processing?

I've been really impressed with the ability of exim to bring my box to it's
knees. Wow this thing is fast, I really like it. But I guess I should make
room for other processes, so I've started tuning it. Here's the scenario at
the moment:

We have one list with about 4500 people on it.
Everyday at around 6AM we send about 50 messages to it. This adds up pretty
quickly.

The machine also processes mail-archive stuff too (This comes into the
machine, and then gets written to a file).

What I would like to do is slowly process those large mail-list items (so as
not to kill the box) while still allowing the archive messages to come
through quickly.

Anyway, I thought I could accomplish this with queue_smtp_domains. In other
words, if it is local, process it right away, if it is smtp, then throw it in
a queue.

Once it is in the queue, process them 3 at a time.

So I did this, and I think it might be working correclty (i.e. the computers
always do what you tell them to). But the system is crawling right now doing
DNS lookups on all the users for all 50 messages, and filling up the log
files with

R=dnslookup T=remote_smtp defer (-1): domain matches queue_smtp_domains, or
-odqs set

The thing is that it is doing this for all 50 messages.

Feel free to tell me I am missing something basic (Newbie to exim).


delay_warning = 0s
deliver_queue_load_max = 99
ignore_bounce_errors_after = 0s
return_size_limit = 10000
#queue_only_load = 3
queue_run_max = 3
smtp_accept_queue = 10
strip_trailing_dot
#split_spool_directory
remote_max_parallel = 9
#queue_only
queue_smtp_domains = *

One possible thought that I had is that it is not queueing these mail lists,
because the mail lists themselves aren't smtp (They are at the end of a
majordomo list). So it doesn't queue the explosions, but it does queue their
result. Am I close to the right track? Does that mean I would then need to
queue everything?

--Brett M. Thorson