An interesting point came up while recently discussing my Postfix virtual_alias issues with the MailScanner list. Apparently there is some risk with the "two instances of postfix" approach described in: http://www.hughesjr.com/content/view/12/30/Guides
It sounds like Postfix and MailScanner can step on each other in the deferred queue. They recommended the single Postfix instance "hold" mechanism recommended here: http://www.sng.ecs.soton.ac.uk/mailscanner/install/postfix.shtml
Here are the steps I used to convert:
1) service MailScanner stop
2) Edit MailScanner.conf and change Incoming Queue Dir = /var/spool/postfix.in/deferred to Incoming Queue Dir = /var/spool/postfix/hold
3) Rename /etc/postfix.in to /etc/postfix.old-in
4) Rename /var/spool/postfix.in to /var/spool/postifx.old-in
5) Edit /etc/postfix/master.cf and uncomment the "smtp inet n - n - - smtpd" that was commented out in Step #12 of the 2-step instructions
6) Edit /etc/postfix/main.cf and add: header_checks = regexp:/etc/postfix/header_checks
7) Create /etc/postfix/header_checks containing: /^Received:/ HOLD
8) service MailScanner start
And you should be back in business. Note that the /etc/init.d/MailScanner script still references both an in and out Postfix instance; however, in looking at the code, once /etc/postfix.in is gone/renamed the "in" startup action becomes a no-op.
I should also point out that there is absolutely NO implied criticism of the SUPERB guides Johnny has put out. I have found them to be extremely helpful -- thanks, Johnny!
Regards, Kennedy