To create an autoresponder or vacation notice on a server using Postfix, I use procmail on an individual account basis. In order to do this, first create a .forward file in the user's home directory with the following (quotes are to be included).

"|IFS=' ' && exec /usr/bin/procmail -f- || exit 75 #tina_fp"

Create a .procmailrc file in the same directory with the following:

SHELL=/bin/sh    # for other shells, this might need adjustment

:0 Whc: vacation.lock
 # Perform a quick check to see if the mail was addressed to us
* $^To:.*\<$\LOGNAME\>
 # Don’t reply to daemons and mailinglists
* !^FROM_DAEMON
 # Mail loops are evil
* !^X-Loop: racktest@fauxpanels.com
| formail -rD 8192 vacation.cache

  :0 ehc         # if the name was not in the cache
  | (formail -rI"Precedence: junk" \
       -A"X-Loop: racktest@fauxpanels.com" ; \
     echo "Hi,"; \
     echo "I will be out of the office from Monday August 2nd to Friday August 6th. "; \
     echo "If you need assistance, please send an email to info@blah.com or call 1-800-555-1212."; \
     echo "-Tina"; \
    ) | $SENDMAIL -oi -t

.

Replace the echo statements with your own reply text.