Simple ListServ

One weekend I was struggling with a Listserv installation. It just didn't do what I wanted it to do, and even worse: somehow, I ended up creating a mail loop that fed hundreds of mail messages into my mailbox in a matter of seconds. I had to stop the mail daemon, clear out all queued messages (hundreds!), clean my mailbox.. Messy. I got sooo fed up, that...

That I decided to cook my own Very Simple Listserv. It's very simple indeed, but - it does what it's supposed to do, and it's very manageable, integrates with SpamAssassin, and it's spam-free (so far). It works. If you're interested, read on.

This mailing list server is intended at small interest groups. It probably won't do too well in high-thruput environments, where thousands of subscribers continuously bombard their groups with mails. But it's simple to set up. If you have an average Linux system, you can be up and running within 5 minutes.

Ingredients

To cook the Simple ListServ, you will need:

• A Unix (Linux) system with sendmail or postfix;
• A Perl interpreter;
• Root access;
• My Perl script that performs the necessary functions, named listhandler and downloaded here.

Recipy

In this recipy we'll cook up a new list, appropriately called "mylist", on a domain "mydomain.org". Just follow the example and supply your own values where appropriate.

• Setting up a list user: As root, do

        adduser -m mylist
      

  I'm assuming that the user's home is /home/mylist; if the home directory is different on your system, adapt where appropriate. Now switch user to the new user:

        su - mylist
      

• The mylist environment: As user user mylist, create a directory spool using:

        mkdir spool
        chmod 777 spool
      

  Also create a directory bin, and copy the script listhandler into the directory.

        mkdir bin
        cp /where/ever/you/put/it/listhandler bin/
        chmod +x bin/listhandler
      

  Next, edit bin/listhandler and modify the configuration at the top to your likings. The configuration items are:
  • $subscriptions: The file with subscriptions. In our example let's take /home/mylist/subscriptions.
  • $debugfile: The file where debugging information is written.
  • $maxdebugsize: The max file size of $debugfile. listhandler will "rotate" the log when its size exceeds this value.
  • $dropspam: Set to 1 if you want spam to be discarded. This works by inspecting the mail header X-Spam-Status in delivered mails. When the value is yes, listhandler simply drops the mail.
  • $mail: Set to your "mail" program, normally /usr/bin/mail.
  • $spool: The "spool" directory, in our example: /home/mylist/spool.
  • $maxmsg: Maximum messages to handle at one time. I have this at 100. When there are more "pending" messages, then listhandler simply won't act. I have this as a protection against mail loops, since I don't expect to be distributing more than 100 messages to each subscriber per run.

  Almost done. Now, edit /home/mylist/subscriptions and add subscribers to mylist@mydomain.org. The format of the list is: one subscriber per line, in the format Firstname Lastname <e-mail@domain>. Empty lines and #-comment is allowed (but the #-sign must be at the first column). For example:

        # /home/mylist/subscriptions: 
        # List of subscribers to mylist@mydomain.org
  
        John Doe <john@somewhere.org>
        Jane Doe <jane@somwhere.else.org>
      

• The mylist e-mail account: Log in as root again. Define an e-mail account mylist that delivers the mail contents to the listhandler script by modifying /etc/aliases:

        echo 'mylist: "|/home/mylist/bin/listhandler accept"' >> /etc/aliases
        newaliases
      

• Testing incoming mail: Now, send a mail to mylist@mydomain.org. When all goes well, you will see a new file in /home/mylist/spool. The file contains a prepared mailing command, and the text that will be mailed.

  You must send the mail as one of the subscribers, in our example as either john@somewhere.org or as jane@somewhere.else.org. Mails from non-subscribers are not accepted by listhandler

  If all goes not well, then:

  • Check /var/log/mail or /var/log/messages for errors that your SMTP program has reported;
  • Check /tmp/mylist.log, the debug-log of listhandler.
• Distributing mail to all subscribers: Now, as user mylist, run:

        /home/mylist/bin/listhandler distribute
      

  This will send queued messages to the subscribers.
• Automating distribution: Now that you've verified it all, add a "crontab" to user mylist. As user mylist, run:

        crontab -e
      

  The line to add should look something like:

        */3 * * * * /home/mylist/bin/listhandler distribute >/dev/null
      

  This runs the distribution process each 3 minutes, every hour, every day.

Bon Appetit

You're all set to use mylist@mydomain.org now. The only thing you'll need to do, is to add or delete subscribers by hand in the file /home/mylist/subscriptions.

Also please note that listhandler doesn't do non-text mail well. It's basically just for text-passing.

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