[Mimedefang] Dedicated Anti-Spam Server Config

[Martin, Jeremy]

Hi there,

Background:

Until recently we have always used Qmail / Qmail-Scanner / ClamAV /
SpamAssassin for our spam/virus filtering. Some friends of ours reported
some incredible performance figures using Sendmail and MIMEDefang so I
have set up a test Sendmail / MIMEDefang / ClamAV / SpamAssassin box to
do some benchmarks. I have got Sendmail/MIMEDefang to scan test messages
ok and its detecting spam ok, but due to my lack of Sendmail experience
I have some questions about how to fine tune the setup.

We use dedicated anti-spam servers as our MX hosts for domains we
spamfilter. The anti-spam servers process the messages, add their
headers to the message to mark each message as spam or not, and then
deliver them to our real mail servers. With our current Qmail setup, one
file "rcpthosts" lists all the domains we are accepting mail for on the
anti-spam server, then another file "smtproutes" lists which servers
each domain's mail should be sent to once it has been processed.

Question:

How do I reproduce this with Sendmail/MIMEDefang - what are the config
options I need to set? I'm pretty sure this has much more to do with
Sendmail and less to do with MIMEDefang, but I couldn't find any active
sendmail mailing lists after a quick search. 

I've seen an example 'gateway.mc' Sendmail config file that has a lot of
different masquerade options set, but I don't think that's what I need
to use since I just want to scan mail for a list of domains and specify
which server to forward it onto once finished, not masquerade all of
them as my primary domain.

Side note: 

Our Qmail server can process about 100 messages per minute with full
remote checks enabled with SpamAssassin, using SQL based user
preferences. Our friends reported scanning 26,000 messages per minute on
a dual-Xeon box with two Sendmail's running, each bound to a separate
Ethernet card, and each bound to a different CPU. I doubt we will see a
full 260x increase since we are having SpamAssassin do full remote
RBL/DNS checks as well as Razor2, Pyzor and DCC, but still it does seem
like Sendmail/MIMEDefang is much faster than Qmail/Qmail-scanner...
which is why I'm here. :-)

Thanks, and sorry if this is too off topic!