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Store SpamAssassin bayes in SQL

[TOC]

Summary

This article will guide you to configure related components to store SpamAssassin Bayes data in SQL server, and allow webmail users to report spam with one click.

Tested with:

  • iRedMail-0.8.0, iRedMail-0.8.7.
  • CentOS 6.2 (x86_64)
  • SpamAssassin-3.3.1
  • Amavisd-new-2.6.6
  • MySQL-5.1.61
  • Roundcubemail-0.7.2

Notes:

  • This article should work with all iRedMail releases. We take iRedMail-0.8.0 for example.
  • This article should work with all backends: OpenLDAP, MySQL, MariaDB, PostgreSQL. We take MySQL backend for example.
  • This article should work with Amavisd-new-2.6.0 and later versions.

IMPORTANT NOTE:

  • The bayesian classifier can only score new messages if it already has 200 known spams and 200 known hams.
  • If Spamassassin fails to identify a spam, teach it so it can do better next time. e.g. Mark it as spam in roundcube webmail.
  • Read References section at the end of this article before asking questions.

Create required SQL database used to store bayes data

We need to create a SQL database and necessary tables to store SpamAssassin bayes data. The RPM package installed on CentOS 6 doesn't ship SQL template for bayes database, so we have to download it from Apache web site. We're running SpamAssassin-3.3.1, so what we need is this SQL template file: http://svn.apache.org/repos/asf/spamassassin/tags/spamassassin_release_3_3_1/sql/bayes_mysql.sql If you're running different version, please find the proper SQL file here: http://svn.apache.org/repos/asf/spamassassin/tags/.

# cd /root/
# wget http://svn.apache.org/repos/asf/spamassassin/tags/spamassassin_release_3_3_1/sql/bayes_mysql.sql

Create MySQL database and import SQL template file:

# mysql -uroot -p
mysql> CREATE DATABASE sa_bayes;
mysql> USE sa_bayes;
mysql> SOURCE /root/bayes_mysql.sql;

Create a new MySQL user (with password sa_user_password) and grant permissions. IMPORTANT NOTE: Please replace password sa_user_password by your own password.

mysql> GRANT SELECT, INSERT, UPDATE, DELETE ON sa_bayes.* TO sa_user@localhost IDENTIFIED BY 'sa_user_password';
mysql> FLUSH PRIVILEGES;

Enable Bayes modules in SpamAssassin

Edit /etc/mail/spamassassin/local.cf, add (or modify below settings):

use_bayes          1
bayes_auto_learn   1
bayes_auto_expire  1

# Store bayesian data in MySQL
bayes_store_module Mail::SpamAssassin::BayesStore::MySQL
bayes_sql_dsn      DBI:mysql:sa_bayes:127.0.0.1:3306

# Store bayesian data in PostgreSQL
#bayes_store_module Mail::SpamAssassin::BayesStore::PgSQL
#bayes_sql_dsn      DBI:Pg:sa_bayes:127.0.0.1:5432

bayes_sql_username sa_user
bayes_sql_password sa_user_password

# Override the username used for storing data in the database.
# This could be used to group users together to share bayesian filter data.
# You can also use this config option to trick sa-learn to learn data as a
# specific user.
#
# In iRedMail, SpamAssassin is called by Amavisd, so we must set it to be
# same as Amavisd daemon user:
#   - on Linux, it's user `amavis`.
#   - on FreeBSD, it's user `vscan`.
#   - on OpenBSD, it's user `_vscan`.
bayes_sql_override_username amavis

Make sure SpamAssassin will load bayes modules:

# /etc/init.d/amavisd stop
# amavisd -c /etc/amavisd/amavisd.conf debug 2>&1 | grep -i 'bayes'
May 16 09:59:33 ... SpamAssassin loaded plugins: ..., Bayes, ...
May 16 10:27:38 ... extra modules loaded after daemonizing/chrooting:
    Mail/SpamAssassin/BayesStore/MySQL.pm, Mail/SpamAssassin/BayesStore/SQL.pm, ...

Looks fine, now press Ctrl-C to terminate above command, and start Amavisd service again normally:

# /etc/init.d/amavisd restart

It is required to initialize the database by learning a message. We use the sample spam email shipped in the RPM package provided by CentOS 6:

# rpm -ql spamassassin | grep 'sample-spam'
/usr/share/doc/spamassassin-3.3.1/sample-spam.txt

# sa-learn --spam --username=vmail /usr/share/doc/spamassassin-3.3.1/sample-spam.txt
Learned tokens from 1 message(s) (1 message(s) examined)

Auto learn spam/ham with Dovecot imap_sieve plugin

Backup your sa_bayes database

Don't forget to update /var/vmail/backup/backup_mysql.sh (or backup_pgsql.sh if you're running PostgreSQL backend) to backup this newly created sa_bayes database. For example:

# Part of file `/var/vmail/backup/backup_mysql.sh`
DATABASES='... sa_bayes'

References