Ubuntu – Postfix won’t start at boot

In /etc/init/rc-sysinit.conf change

start on filesystem and net-device-up IFACE=lo

to

start on filesystem and net-device-up IFACE=eth0

This will fix your 'runlevel' from coming up as unknown. I can't explain it, but I've been wrestling with the same issue. I found the workaround here: http://ubuntuforums.org/showpost.php?p=9213567&postcount=7

As a result your init scripts will work again. For me it was affecting virtualbox-ose, mysql, and cups.

chkconfig --add postfix require a postfix init script inside init script repositories, commonly /etc/init.d.

chkconfig and update-rc.d (debian) just manipule scripts in /etc/rc#.d/, where # is the startup runrelevel that the default is set on /etc/inittab on line with initdefault term. Im my case is:

id:2:initdefault:

Then the symbolics links on /etc/rc2.d/ will be called. The name of this links have a pattern [S|K]\d{1,}dstname, e.g:

$ ls -l /etc/rc2.d/ | grep postfix
lrwxrwxrwx 1 root root  17 Ago 16 09:04 S22postfix -> ../init.d/postfix

S means /etc/init.d/postfix start K means /etc/init.d/postfix stop

22 is the links execution order.

Then you need check inittab to get default run level (initdefault), check the links on /etc/rcX.d (X is initdefault value), and have the link with a postfix startup script as target ( a script that supportstartfor S prefix links andstop` for K prefix links args).

This is how initsysv system works, but each distro can change a little.