I have recently been moving some sites from shared hosting to my vps. And one of the benefits of shared hosting is a shiny cpanel installation which provides controls for working with email. Something which a barebones vps installation lacks. (Which is not a bad thing
Whilst it is good to have postfix configured so your site can send email I am now of the mind that it is easier and a better use of resources to outsource the incoming email to google apps.
It is still free for the time being and all you need to do is add a few MX records to allow google to handle your mail and you are cooking on gas.
Also there is the ability to create domain aliases, so you can have multiple domains running through one google apps account. (Assuming you want to do this).
I was too short on time to learn the ins and outs of postfix so im using yet another google web service solved my problems.