[Mimedefang] Network effects (was Re: ERR Filter timed out)

[Brian Landers]

> Any kind of network-based check is prone to this error.  You have no
> control over how long DNS lookups take, and they can easily cause a
> filter timeout.  If you absolutely must use network lookups, then set
> the busy timeout to something big like 30 minutes, and do the same in
> your Sendmail configuration file (see the INPUT_MAIL_FILTER
> documentation.)

Another option is to run a local caching DNS server on your mail server
itself, and set /etc/resolv.conf to use 127.0.0.1 as primary nameserver.
This will help not only mimedefang/spamassassin but sendmail itself. I
personally run dnscache (http://cr.yp.to/djbdns.html) on my relays and
it definitely makes an difference in performance.  BIND would work as
well, of course.

*brian