From LedHed's Wiki
Creating the Vacation User/Group
groupadd vacation useradd -s/sbin/nologin -d/nonexistent -g vacation vacation
See [User Management] for more information on creating users in linux
Creating Directories
mkdir -p /var/spool/vacation cp /tmp/postfixadmin-2.1.0/VIRTUAL_VACATION/vacation.pl /var/spool/vacation chown -R vacation.vacation /var/spool/vacation chmod -R 700 /var/spool/vacation
Postfix Intigration
Edit /etc/postfix/master.cf Add these lines at the bottom.
### Postfix Admin Vacation Message vacation unix - n n - - pipe flags=Rhu user=vacation argv=/var/spool/vacation/vacation.pl