When trying to enable vacation/out-of-office support to our PostfixAdmin setup, I came across an error in /var/log/maillog:

Jun 19 11:52:10 host postfix/qmgr[5084]: warning: connect to transport vacation: No such file or directory

Turns out there is a typo in VIRTUAL_VACATION/INSTALL.txt. It tells you to add a service named “filter” to your master.cf file, but it should actually be named “vacation” like so:

vacation unix - n n - - pipe
flags=DRhu user=vacation argv=/var/spool/vacation/vacation.pl