How To Install and Setup Spamassassin on Ubuntu 12.04

Status: Deprecated

This article covers a version of Ubuntu that is no longer supported. If you are currently operate a server running Ubuntu 12.04, we highly recommend upgrading or migrating to a supported version of Ubuntu:

• Upgrade to Ubuntu 14.04.
• Upgrade from Ubuntu 14.04 to Ubuntu 16.04
• Migrate the server data to a supported version

Reason: Ubuntu 12.04 reached end of life (EOL) on April 28, 2017 and no longer receives security patches or updates. This guide is no longer maintained.

See Instead:
This guide might still be useful as a reference, but may not work on other Ubuntu releases. If available, we strongly recommend using a guide written for the version of Ubuntu you are using. You can use the search functionality at the top of the page to find a more recent version.

About Spamassassin

Spamassassin is a free and open-source mail filter written in Perl that is used to identify spam using a wide range of heuristic tests on mail headers and body text. It will save your mailbox from much unwanted spam emails.

Prerequisites

Before installing Spamassassin, you need to install and setup a mail transfer agent such as Postfix on your virtual private server.

You can find instructions on that here

Install Spamassassin

Use apt-get to install Spamassassin and spamc.

apt-get install spamassassin spamc

Once Spamassassin is installed, there are a few steps that has to be taken to make it fully functional.

Adding Spamassassin User

To run Spamassassin you need to create a new user on your VPS.

First add the group spams:

groupadd spamd

then add the user spamd with the home directory /var/log/spamassassin:

useradd -g spamd -s /bin/false -d /var/log/spamassassin spamd

then create the directory /var/log/spamassassin:

mkdir /var/log/spamassassin

and change the ownership of the directory to spams:

chown spamd:spamd /var/log/spamassassin

Let's set up Spamassassin now.

Setting Up Spamassassin

Open the spamassassin config file using:

nano /etc/default/spamassassin

To enable Spamassassin find the line

ENABLED=0

and change it to

ENABLED=1

To enable automatic rule updates in order to get the latest spam filtering rules find the line

CRON=0

and change it to

CRON=1

Now create a variable named SAHOME with the Spamassassin home directory:

SAHOME="/var/log/spamassassin/"

Find and change the OPTIONS variable to

OPTIONS="--create-prefs --max-children 2 --username spamd \
-H ${SAHOME} -s ${SAHOME}spamd.log"

This specifies the username Spamassassin will run under as spamd, as well as add the home directory, create the log file, and limit the child processes that Spamassassin can run.

If you have a busy server, feel free to increase the max-children value.

Start the Spamassassin daemon by using the following code:

service spamassassin start

Now, let's config Postfix.

Configuring Postfix

The emails still do not go through Spamassasin. To do that, open Postfix config file using:

nano /etc/postfix/master.cf

Find the the line

smtp      inet  n       -       -       -       -       smtpd

and add the following

-o content_filter=spamassassin

Now, Postfix will pipe the mail through Spamassassin.

To setup after-queue content filter add the following line to the end of the file

spamassassin unix -     n       n       -       -       pipe
        user=spamd argv=/usr/bin/spamc -f -e  
        /usr/sbin/sendmail -oi -f ${sender} ${recipient}

For the changes to take effect restart postfix:

service postfix restart

Now postfix will use spamassassin as a spam filter.

Configuring Spamassassin on your VPS

To get the maximum use of Spamassassin you have to create rules.

Open the Spamassassin default rules file using:

nano /etc/spamassassin/local.cf

To activate a rules uncomment line remove the # symbol.

To add a spam header to spam mail uncomment or add the line:

rewrite_header Subject [***** SPAM _SCORE_ *****]

Spamassassin gives a score to each mail after running different tests on it. The following line will mark the mail as spam if the score is more than the value specified in the rule.

required_score           3.0

To use bayes theorem to check mails, uncomment or add the line:

use_bayes               1

To enable bayes auto learning, uncomment or add the line:

bayes_auto_learn        1

After adding the above details, save the file and restart spam assassin.

service spamassassin restart

Testing

To see if Spamassassin is working, you can check the spamassassin log file using:

nano /var/log/spamassassin/spamd.log

or send the email from an external server and check the mail headers.

Conclusion

Using Spamassassin, it is very easy to protect your mailbox from spammers. The best thing about Spamassassin is that we can create rules by ourselves and manage it. If you have a mail server, then you must also have Spamassassin!

root      8302     1  8 00:27 ?        00:00:00 /usr/sbin/spamd -d --pidfile=/var/run/spamassassin.pid --create-prefs --max-children 5 --username spamd --helper-home-dir ${SPAMD_HOME} -s ${SPAMD_HOME}spamd.log

# /etc/default/spamassassin
# Duncan Findlay

# WARNING: please read README.spamd before using.
# There may be security risks.
# If you're using systemd (default for jessie), the ENABLED setting is
# not used. Instead, enable spamd by issuing:
# systemctl enable spamassassin.service
# Change to "1" to enable spamd on systems using sysvinit:
ENABLED=1

# Options
# See man spamd for possible options. The -d option is automatically added.

# SpamAssassin uses a preforking model, so be careful! You need to
# make sure --max-children is not set to anything higher than 5,
# unless you know what you're doing.

#OPTIONS="--create-prefs --max-children 5 --helper-home-dir"
SPAMD_HOME="/home/spamd"
#OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir ${SPAMD_HOME} -s ${SPAMD_HOME}/spamd.log"
OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir /home/spamd -s /home/spamd/spamd.log"

# Pid file
# Where should spamd write its PID to file? If you use the -u or
# --username option above, this needs to be writable by that user.
# Otherwise, the init script will not be able to shut spamd down.
#PIDFILE="/var/run/spamd.pid"
#PIDFILE="${SPAMD_HOME}/spamd.pid"
PIDFILE="/home/spamd/spamd.pid"
# Set nice level of spamd
#NICE="--nicelevel 15"

# Cronjob
# Set to anything but 0 to enable the cron job to automatically update
# spamassassin's rules on a nightly basis
CRON=1

-o content_filter=spamassassin

/usr/sbin/postconf: fatal: file /etc/postfix/master.cf: line 17: bad field count

  -o content_filter=spamassassin