Postfix can be handled slightly differently from the other supported
mail systems, as one copy of Postfix can handle both the incoming mail
via SMTP,and the outgoing mail by doing all the delivery.
How to Set Up Postfix for MailScanner Use

1. Install Postfix version 2 and get it all working.
2. Stop Postfix using a command
postfix stop
3. Make sure you have the chroot jail set up in /var/spool/postfix.
You should be able to see "etc", "usr" and "lib" directories inside
/var/spool/postfix). If you haven't got the chroot jail setup
already, then look in the "examples" directory of the Postfix
documentation and you will find a script in there to set up it up for
your operating system. If you can't find that, then see the "Problems
or Errors" section further down this page.
4. At this point, things change from the setup for other MTAs as we
can make it run with just one copy of Postfix, and let Postfix do the
"split MTA" setup for us.
5. In the Postfix configuration file /etc/postfix/main.cf add this
line: header_checks = regexp:/etc/postfix/header_checks
6. In the file /etc/postfix/header_checks add this line:
/^Received:/ HOLD The effect of this is to tell Postfix to move all
messages to the HOLD queue.

How to Set up MailScanner for Use with Postfix

In your MailScanner.conf file (probably in /etc/MailScanner or
/opt/MailScanner/etc), there are 5 settings you need to change. They
are all really near the top of the file. The settings are

Run As User = postfix
Run As Group = postfix
Incoming Queue Dir = /var/spool/postfix/hold
Outgoing Queue Dir = /var/spool/postfix/incoming
MTA = postfix

You will need to ensure that the user "postfix" can write to
/var/spool/MailScanner/incoming and /var/spool/MailScanner/quarantine:

chown postfix.postfix /var/spool/MailScanner/incoming
chown postfix.postfix /var/spool/MailScanner/quarantine

If you upgrade your copy of MailScanner, unfortunately these
directories will be changed back to being owned by root, so you will
have to do those 2 commands again.

Starting It All Running If on a system installed using the RedHat RPM
distribution, just use the init.d script to do it all for you:
/etc/rc.d/init.d/MailScanner start (or on RedHat systems just service
MailScanner start) If not using the RedHat RPM distribution, then

1. Start Postfix
postfix start
2. Start MailScanner
check_MailScanner