How does Postfix get started?

[Jerry LeVan]

Hi,

I just bought a Mac Book Pro, regrettably the Migration Assistant
was not able to function with my setup).

I have most of the stuff that I need moved to the MPB via
brute force...

One thing I found sorta mysterious was how the Postfix mail
transfer agent actually got started.

On my old G4, to the best of my knowledge, the critical
step was to set:
     MAILSERVER=-YES-
in /etc/hostconfig. ( And do some stuff with the config files...)

When I tried to do the same on the MBP and rebooted, I found that
postfix was not started.

I went back and tried to find exactly where postfix gets started on  
the G4
during the boot process and could find no trace of how it get
kicked off! ( I browsed the rc stuff in /etc and peeked at the
startup items in /System/Library and /Library...)

Of course I have spent the better part of two days getting the
new MBP config'ed so fatigue might be playing a factor...

The only way I could get postfix running on the MBP was to
create a rc.local and stick the command:
      /usr/sbin/postfix start
into the file.

Can anyone enlighten me ie hit me with a clue stick on how
postfix is supposed to be started?