HOWTO: on vacation autoreply with Postfix/LDAP and Gnarwl

If your users are asking for an autoreply feature when they’re on vacation, and you are currently using postfix as MTA with a LDAP backend for authentication, IMO the best solution is to use Gnarwl and configure it following these simple steps:

• download the most recent Gnarwl’s tarball in a place of choice
• unpack it and install it with
  ./configure
make
make install
make perm
  this will install Gnarwl under /usr/local and do all the dirty work (creating the gnarwl local user for example, check your /etc/passwd )
• edit /usr/local/etc/gnarwl.cfg to look like this:
map_sender $sender
map_receiver $recepient
map_subject $subject
map_field $fullname cn
server your.ldap.server.com
port 389
scope sub
protocol 3
base ou=Users,dc=YOURCOMPANY,dc=com
queryfilter (&(mail=$recepient)(vacationActive=active))
result vacationInfo
blockfiles /usr/local/var/lib/gnarwl/block/
umask 0644
blockexpire 6
mta /usr/sbin/sendmail -t $recepient
maxreceivers 64
maxheader 512
charset ISO8859-15
badheaders /usr/local/var/lib/gnarwl/badheaders.db
blacklist /usr/local/var/lib/gnarwl/blacklist.db
forceheader /usr/local/var/lib/gnarwl/header.txt
forcefooter /usr/local/var/lib/gnarwl/footer.txt
recvheader To Cc

  vacationActive and vacationInfo are two attibutes that have to exist in the LDAP schema you’re using for your users. Obviously you can use whatever attribute you prefer, you simple have to literally change the vacationActive/vacationInfo in this config with your own attributes, keeping in mind that vacationActive is used to check if autoreply is enabled or not for that particular user and vacationInfo it’s the text that is being used as a reply (note: you can use CR/LF in it, to obtain a multiline text). The other parameter that deserves a comment is blockexpire: here you can put the amount of time (in hours) during wich an autoreply to the same sender will not be sent. For example, if john@foo.com tries to send a mail to duke@yourcompany.com, he will receive the vacation message. But, as in our config example, john sends another message within 3 hours, he won’t get any message at all. He has to wait 3 more hours to get notified again (blockexpire was set to 6 hours, remember)
• as the doc/INSTALL file in Gnarwl says, the quick-and-dirty way to enable Gnarwl in a postfix installation (this is the method I’m using, too :) is to edit /etc/postfix/main.cf and simply add the linealways_bcc=gnarwlThis works by delivering every message to the local gnarwl user (even if you are in a virtual environment), which has a .forward file that pipes everything to the gnarwl binary program, which takes care of everything
• Now, the final step: to activate the vacation message for one of your customer, simply edit your LDAP data, add a vacationActive attribute with an “active” value to the user you want, and add vacationInfo with the text you want. That’s all.

For more info and more detailed configuration instructions, please refer to the doc/INSTALL file in your gnarwl tarball.