ciao
ho cominciato a documentarmi in giro e in un how-to
You MUST have a working DNS, and your system must have a DNS name. qmail does not search an /etc/hosts file in order to look up domain names. A workaround is possible using smtproutes, but doing this is not recommended, or desirable in most cases.
non ben capito...la macchina deve essere un server DNS?

quindi non si basa su /etc/resolv.conf?