Automate the installation of postfix on Ubuntu
You can use pre-seeding for this, using the debconf-set-selections command to pre-answer the questions asked by debconf before installing the package.
For example:
debconf-set-selections <<< "postfix postfix/mailname string your.hostname.com"
debconf-set-selections <<< "postfix postfix/main_mailer_type string 'Internet Site'"
apt-get install --assume-yes postfix
If you want this globally:
dpkg-reconfigure debconf
Then configure it to be "noninteractive"
If you just want it for single install run:
DEBIAN_FRONTEND=noninteractive apt-get install PACKAGE