hey there,

Nice work.
I have couple of comments/queries. 
I was wondering about this setup in production environment. I mean u patched postfix manually. I would be suprized if "urpmi update" doesn't break postfix.

And btw could http://postfixadmin.sourceforge.net/ play any constructive role in all this setup. (i.e. in easing out the configuration process).

Usually my main concern, after stability/security/support(packages), is how soon I can get the system back up whenever it crashes on me. (apart from clonezilla i.e)

Cheers.