November 15 2011 17:30 CET
Debian and Ubuntu should be able to handle
dpkg installs non-interactively by specifying a variable for
postfix seems not to respect this and starts whiptail to ask you whether the machine is “an internet site” etc.
The trick is to prepopulate
After this you should be able to do this:
DEBIAN_FRONTEND='noninteractive' apt-get install -y -q --force-yes postfix
Live long and prosper :)