From: [email protected]
Date: 2018-05-15
Subject: Installing Postfix and Mailman on Debian Jessie

I  recently  set up Mailman, a mailing list manager, on a small VPS
running Debian GNU/Linux.  I also set up Postfix  as  my  MTA.   It
took  me  a week of evenings and I had a hard time getting it done.
I collected my notes along the way so that they may benefit someone
else.

I've  organized  my notes as a commentary on the official installa-
tion documentation.  The official documentation  is  comprehensive,
but  it makes a number of assumptions that don't apply to this par-
ticular installation scenario.  I hope my commentary can act  as  a
helping  hand  for  those  in  a similar situation (i.e. installing
Mailman 1.2.1 and Postfix 2.11.3 using apt on Debian  8  (Jessie)).
As you read the Postfix Basic Configuration [1] and the GNU Mailman
Installation Manual [3] you can refer to my notes on each  section,
below.   This  is  not  a  complete guide and won't make much sense
without the installation manual.

Note that I already had Python  2.7.9,  Apache  2.4.10,  and  msmtp
1.4.32 installed and configured.  I have also registered my domain,
example.com, and set up a DNS A record that points  example.com  to
my  VPS.   I  want to host my lists at lists.example.com which will
require me to use a virtual domain.  I'm  using  example.com  as  a
placeholder.   You  will need to use your chosen domain during your
installation.

                       Basic Installation

To install Mailman and Postfix using apt, I typed

      sudo apt install mailman postfix

at the command line.  The Postfix installer asked me to  provide  a
FQDN.   I  gave  it example.com.  Mailman asked me to select a lan-
guage.  I selected English.

                      Postfix Configuration

I followed the Postfix Basic Configuration [1] guide.   I  reviewed
all the defaults and almost all of them looked correct for my situ-
ation.  In /etc/postfix/main.cf, I added

    mydomain = example.com

Looking at the chroot discussion, the readme suggests that "Postfix
daemons  that  deliver mail locally" can't be run chrooted.  I will
certainly be delivering mail locally.

I also created an MX record for example.com and opened port  25  to
TCP  connections.   At  this  point,  you should be able to restart
Postfix

    sudo /etc/init.d/postfix restart

and send a test email to a local user (e.g. [email protected]).

If your test fails, refer to the Troubleshooting section at the end
of this document.

                      Mailman Configuration

# 1 Installation Requirements

We  are  not going to be installing from source, but do verify that
you have a recent patch of python 2.7 installed.  As I write  this,
the  Mailman wiki recommends Python 2.7.14.  I had Python 2.7.9 in-
stalled.

This section also says, "you will need an ANSI C compiler to  build
Mailman's  security  wrappers."   I assume this only applies if you
are installing from source.  I  didn't  compile  anything  directly
during this process.

# 2 Set up your system

The  manual  suggests  creating a user and group called mailman.  I
installed Mailman using apt.  This install process created the list
user and group, so I didn't need to create any users or groups, and
I didn't have to create an  installation  directory  or  manipulate
permissions at this point.

# 3 Build Mailman

I didn't install from source, so there's no need to do any of this.

# 4 Check your installation

I  ran  check_perms  with  the -f switch, but I still had to change
some files manually so that they were owned by root:list.   For  my
installation, the value of $prefix was /usr/lib/mailman.

# 5 Set up your web server

The  Debian distribution of Mailman comes with a sample apache.conf
file that is actually fairly complete for this purpose.  I  started
by appending those settings to my apache2.conf file.

    cat /etc/mailman/apache.conf >> /etc/apache2/apache2.conf

This  covered the majority of the individual steps in this section.
I had to change occurrences of

    Order allow,deny
    Allow from all

to

    Require all granted

It's not addressed in the installation manual, but I had to  enable
the Apache CGI module.

    sudo a2enmod cgid

Before  I  did  this, apache was serving up binary files instead of
running scripts.

I continued to have problems until I restarted my browser.

In /etc/mailman/mm_cfg.py I added

    DEFAULT_EMAIL_HOST = 'lists.example.com'
    DEFAULT_URL_HOST = 'lists.example.com'
    DEFAULT_URL_PATTERN = 'http://%s/cgi-bin/mailman/'

and commented out the existing settings for those values.

I restarted apache with

    sudo apachectl restart

but you could also use

    sudo /etc/init.d/apache restart

Apache says, "AH00112: Warning: DocumentRoot [/var/www/lists]  does
not exist" which makes sense since there's no such folder.

I   can  now  access  my  Mailman  web  interface  at  http://exam-
ple.com/cgi-bin/mailman/admin.

I found that the create list function was  publicly  available.   I
didn't  want that, so I had to disable it.  I didn't find a cleaner
way to do this, I  just  changed  the  permissions  on  the  create
script.

    sudo chmod o-x /usr/lib/cgi-bin/mailman/create

# 6 Set up your mail server

I'm using Postfix because I heard it was the easiest to set up.

## 6.1 Using the Postfix mail server

The only thing I did in this section was add

    unknown_local_recipient_reject_code = 550

to /etc/postfix/main.cf.

### 6.1.1 Integrating Postfix and Mailman

I have a number of notes on this section.

Debian  includes  a  script,  postfix-to-mailman.py, that claims to
make alias management easier.  I did not have success with  it.   A
number  of  sources  I  found indicated that using postfix-to-mail-
man.py is neither supported nor recommended.  My advice is  to  ig-
nore  it  and  stick to the official install manual.  The script is
only distributed with Debian distributions of Linux.

I don't understand why 6.1.1 and 6.1.2 are not  reversed.   If  you
are  using  virtual domains (e.g. lists.example.com), then you will
need to configure them in Mailman before you can generate  aliases.
If you are using virtual domains, you'll need to skip ahead to sec-
tion 6.1.2 and then come back here.

There is a typo in section 6.1.1 in the note that recommends  read-
ing  the  next section first.  The copy says, "read the 6.1 section
below first," but the link points to section 6.1.2.

After   setting   MTA   =   'Postfix'   in   /usr/lib/mailman/Mail-
man/mm_cfg.py,  and before running genaliases, you need to create a
list in your virtual domain.  Something like:

    newlist -e lists.example.com testlist

Now, when you run genaliases,

    sudo /usr/lib/mailman/bin/genaliases

it should create

    /var/lib/mailman/data/aliases
    /var/lib/mailman/data/aliases.db
    /var/lib/mailman/data/virtual-mailman
    /var/lib/mailman/data/virtual-mailman.db

Note  that,  though   the   install   location   for   Mailman   is
/usr/lib/mailman,  the  map  files  created  by  genaliases live in
/var/lib/mailman/data.

I changed the ownership and permissions on these files.

    sudo chown list:list /var/lib/mailman/data/{aliases,aliases.db,virtual-mailman,virtual-mailman.db}
    sudo chmod g+w /var/lib/mailman/data/{aliases,aliases.db,virtual-mailman,virtual-mailman.db}

Restart Postfix

    sudo /etc/init.d/postfix restart

Restart Mailman

    sudo /etc/init.d/mailman restart

### 6.1.2 Virtual domains

If you are using virtual domains,  (e.g.  lists.example.com),  then
DNS  will need to be working for these domains.  My domain configu-
ration at the registrar refers to my VPS provider's  name  servers.
In  my  VPS's DNS configuration, I added DNS records for my virtual
domain.

    added A record for lists.example.com
    added mx record for lists.example.com

In /usr/lib/mailman/Mailman/mm_cfg.py add

    MTA='Postfix'
    POSTFIX_STYLE_VIRTUAL_DOMAINS=['lists.example.com']

Setting up virtual alias domains in Postfix involved:

Update alias maps in /etc/postfix/main.cf

    alias_maps = hash:/etc/aliases,hash:/var/lib/mailman/data/aliases
    alias_database = hash:/etc/aliases
    virtual_alias_domains = lists.example.com
    virtual_alias_maps = hash:/var/lib/mailman/data/virtual-mailman

I copied /etc/aliases to /var/lib/mailman/data/aliases, but I'm not
sure it was necessary.

Now, return to 6.1.1 to create your list and generate aliases.

# 7 Review your site defaults

I skipped this part, assuming that the defaults would be fine.

# 8 Create a site-wide mailing list

In /usr/lib/mailman

    sudo bin/newlist mailman

                         Troubleshooting

At this point, you should have a working Mailman server. If you are
not getting mail, but think you should, here's where to start.

 * You should be able to open a telnet connection  to  lists.exam-
ple.com  on port 25. If you can't, check your DNS and firewall set-
tings.
 * Check your spam folder!
 * You can inspect mail that  is  queued  for  delivery  by  using
`mailq`  or  `/usr/sbin/postqueue  -p`.  They appear to do the same
thing.
 * You can inspect mail system activity at  /var/log/mail.log.  If
you  can  spare a window, you might run `tail -f /var/log/mail.log`
to keep an eye on things.

                           Wait. Why?

It has been pointed out to me that maintaining a mailing  list  can
be  a  lot of work.  There are security issues to think about, spam
to fight, upgrades to apply, and let's just ignore the  human  ele-
ment  for now.  I agree that to do this right can be a lot of work.
From a practical perspective, I'm taking this one step at  a  time.
At a higher level, this is an expression of my dissatisfaction with
a toxic social media environment.  I want to  see  a  return  to  a
state  where  these  communication mediums are built and maintained
for the benefit of all.

                           References

Here's a pile of resources that I found during this adventure.

1. http://www.postfix.org/BASIC_CONFIGURATION_README.html
2. https://www.linux.com/learn/install-and-configure-postfix-mail-server
3. http://list.org/mailman-install/
4. https://askubuntu.com/questions/422689/mailman-web-interface-not-working
5. https://mail.python.org/pipermail/mailman-users/2007-April/056639.html
6. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718284
7. https://serverfault.com/questions/735559/early-mail-rejection-with-mailman-in-postfix
8. https://serverfault.com/questions/534649/postfix-and-mailman
9. https://stackoverflow.com/questions/27431010/postfix-mailman-recipient-address-rejected-user-unknown-in-local-recipient-tab
10. https://wiki.list.org/DOC/How%20do%20I%20configure%20postfix_to_mailman.py%3F
11. http://www.postfix.org/qmgr.8.html
12. http://www.postfix.org/trivial-rewrite.8.html
13. http://www.postfix.org/transport.5.html
14. http://www.postfix.org/virtual.5.html
15. http://www.postfix.org/VIRTUAL_README.html
16. https://www.suse.com/support/kb/doc/?id=3279773
17. https://mail.python.org/pipermail/mailman-users/2007-April/056640.html
18. https://mail.python.org/pipermail/mailman-users/2012-October/074154.html
19. https://www.gnu.org/software/mailman/mailman-admin.pdf
20. https://wiki.list.org/DOC/Making%20Sure%20Your%20Lists%20Are%20Private

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