Originally Posted by micko_escalade
1. What's the difference between BIND+Dovecot and MyDNS+Courier? which one is better?
Both work equally good; personally, I'd go for BIND + Courier, but that's just my preference.
If the VM is in a LAN, you can use an unused local IP. If it's not in a LAN, and you just have one public IP which in in use already by the host, then you need to get another public IP.