Hi Christoph
> I never knew that this is possible. I only use it via unix domain
> socket. Can you sent me a configuration example for sendmail and
> mimedefang using IP connections?
Sure...
MIMEDefang (spamassassin / virus scanning) cause high IO, Memory and CPU load
on the machine doing the filtering. Sharing this load on multiple designated
milter machines would take the load of the actual mailserver and spread this
load among multiple machines increasing overal performance. This scales very
well.
Unfortunately my actual working config is installed from the sources. I just
wanted to try to migrate to the Debian Packages so I don't have to worry
about updates :-)
Assume, you have one Mailserver (mx.example.com 192.168.0.1) and three Milter
Machines (filter.example.com 192.168.0.10 192.168.0.11 192.168.0.12).
On the three milter Machines (which don't need sendmail to be installed) you
use:
In mimedefang.conf (or /etc/init.d/mimedefang or wherever you set the
MIMEDefang variables).
# SOCKET=$SPOOLDIR/mimedefang.sock
SOCKET=inet:3
(and you make sure by using iptables that only mx.example.com is allowed to
connect).
On the MX you configure sendmail to connect to the round robin DNS name of
those milters: sendmail.mc
INPUT_MAIL_FILTER(`mimedefang', `S=inet:[EMAIL PROTECTED], F=T,
T=S:600s;R:600s;E:10m')
So you get some nice load balancing.
If you want to scale the environement you can add more milter machines or even
more MXes connecting to this milter 'cluster'.
Another advantage ist, you can take down one milter machine without the
operation of the mail-servers being affected. (by using round-robin DNS
sendmail automaticly reconnects to the next IP if one reports unreachable).
Mit freundlichen GrĂ¼ssen
Benoit Panizzon
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