In order to setup automatic email response (in what follows, USER refers to your username):
Edit your vacation message
/home/USER/.procmail/vacation.msg as appropriate. This file should be text only. It may not contain any variables such as $SUBJECT or $DATE.
Uncomment this line to be found in either your
#INCLUDERC=$PMDIR/rc.vacation #this line is commented
/home/USER/vacation.cache if it exists.
To remove automatic email response when you return:
Comment the line you uncommented above when setting up vacation messaging.
/home/USER/vacation.cache. This file contains a list of people to whom vacation messages have already been sent. Next time you set up vacation, you don't want to start with an old list.