[Mimedefang] Performance Tweaking

[Fox, Randy]

We have recently added a process that sends out 10's of thousands of messages in a rather short period to our customers.   Consequently, I've been doing a lot of work to improve the performance of the servers.  I've found that I can do a lot by adjusting sendmail's RefuseLA and QueueLA parameters.  I've also started using multiplexor's -M option.  After some trial-and-error, I've limited MD to 30MB of RAM and have sendmail's Load Averages set at 70 and 75.  I'm wondering, what kind of error messages/behavior can I expect when the memory limit is reached?

I would like to not have MIMEDefang process any messages from the server producing the messages so I've set a global variable in filter_begin if the message from these servers:

    $PROD_MAIL = 0;
    if ($RelayHostname =~ /^prodserver.localdomain.com$/) {
        $PROD_MAIL = 1;
    }

I then check $PROD_MAIL very early in filter and filter_end and exit the subs if it is set:

    return if $PROD_MAIL;

Is there possibly an even more efficient method to minimize the impact if MD of messages from this server?

BTW, the tweaking has helped immensely.  Last month during our first peak day, the load of messages spread pretty evenly between 3 servers, this morning 1 server did about 90% of the work.

Randy