[CentOS] Advise on RPM vs. Compiling source

> Your standard modus operandi should be installing from the CentOS
> repositories with yum. It is the only thing that is supported and
> well-tested. It is also the only way to automatically get security
> updates for Postfix from the CentOS project through yum.

Just on this point, I want to say that I have not seen a security update 
on postfix in years.