Posted by Admin on April 1st, 2008<\/p>\n
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We have already discussed how to install mail server with postfix+Devcot+SASL+Squirrel Mail in this article we will see how to add spam filter for postfix mail server.<\/p>\n
Apache SpamAssassin is an extensible email filter that is used to identify spam. Once identified, the mail can then be optionally tagged as spam for later filtering. It provides a command line tool to perform filtering, a client-server system to filter large volumes of mail, and Mail::SpamAssassin, a set of Perl modules allowing Apache SpamAssassin to be used in a wide variety of email systems.<\/p>\n
Install Spamassassin in Debian<\/p>\n
#apt-get install spamassassin spamc<\/p>\n
spamassassin package can also be integrated into a Mail Transport Agent such as postfix.<\/p>\n
Preparation<\/p>\n
By default Spamassassin will run as root users when you install from debian repository and is not started to avoid that, we are going to create a specific user and group for spamassassin.<\/p>\n
#groupadd -g 5001 spamd<\/p>\n
#useradd -u 5001 -g spamd -s \/sbin\/nologin -d \/var\/lib\/spamassassin spamd<\/p>\n
#mkdir \/var\/lib\/spamassassin<\/p>\n
#chown spamd:spamd \/var\/lib\/spamassassin<\/p>\n
we need to change some settings in \/etc\/default\/spamassassin and make sure you get the following values<\/p>\n
ENABLED=1
\nSAHOME=\u201d\/var\/lib\/spamassassin\/\u201d
\nOPTIONS=\"--create-prefs --max-children 5 --username spamd --helper-home-dir ${SAHOME} -s ${SAHOME}spamd.log\"
\nPIDFILE=\u201d${SAHOME}spamd.pid\u201d<\/p>\n
We are going to run spamd daemon as user spamd and make it use its own home dir (\/var\/lib\/spamassassin\/) and is going to output its logs in \/var\/lib\/spamassassin\/spamd.log<\/p>\n
spamassassin Configuration<\/p>\n
we need to give spamassassin some rules. The default settings are quite fine, but you might tweak them up a bit. So let\u2019s edit \/etc\/spamassassin\/local.cf and make it looks like that<\/p>\n
#vi \/etc\/spamassassin\/local.cf<\/p>\n
Modify this file looks like below<\/p>\n
rewrite_header Subject [***** SPAM _SCORE_ *****]
\nrequired_score 2.0
\n#to be able to use _SCORE_ we need report_safe set to 0
\n#If this option is set to 0, incoming spam is only modified by adding some \u201cX-Spam-\u201d headers and no changes will be made to the body.
\nreport_safe 0<\/p>\n
# Enable the Bayes system
\nuse_bayes 1
\nuse_bayes_rules 1
\n# Enable Bayes auto-learning
\nbayes_auto_learn 1<\/p>\n
# Enable or disable network checks
\nskip_rbl_checks 0
\nuse_razor2 0
\nuse_dcc 0
\nuse_pyzor 0<\/p>\n
we set spamassassin\u2019 spamd default settings to rewrite email subject to [***** SPAM _SCORE_ *****], where _SCORE_ is the score attributed to the email by spamassassin after running different tests, only if the actual score is greater or equal to 2.0. So email with a score lower than 2 won\u2019t be modified.<\/p>\n
To be able to use the _SCORE_ in the rewrite_header directive, we need to set report_safe to 0.<\/p>\n
In the next section, we tell spamassassin to use bayes classifier and to improve itself by auto-learning from the messages it will analyse.<\/p>\n
In the last section, we disable collaborative network such as pyzor, razor2 and dcc. Those collaborative network keep an up-to-date catalogue of know mail checksum to be recognized as spam. Those might be interresting to use, but I\u2019m not going to use them here as I found it took long enough to spamassassin to deal with spams only using it rules.<\/p>\n
Restart spamassassin using the following command<\/p>\n
#\/etc\/init.d\/spamassassin start<\/p>\n
Configuring Postfix call Spamassassin<\/p>\n
spamassassin will be invoked only once postfix has finished with the email.<\/p>\n
To tell postfix to use spamassassin, we are going to edit \/etc\/postfix\/master.cf<\/p>\n
#vi \/etc\/postfix\/master.cf<\/p>\n
Change the following line<\/p>\n
smtp inet n - - - - smtpd<\/p>\n
to<\/p>\n
smtp inet n - - - - smtpd
\n-o content_filter=spamassassin<\/p>\n
and then, at the end of master.cf file add the following lines<\/p>\n
spamassassin unix - n n - - pipe<\/p>\n
user=spamd argv=\/usr\/bin\/spamc -f -e
\n\/usr\/sbin\/sendmail -oi -f ${sender} ${recipient}<\/p>\n
Save and exit the file<\/p>\n
That\u2019s it our spam filter is setted up, we need to reload postfix settings and everything should be ready.<\/p>\n
#\/etc\/init.d\/postfix reload<\/p>\n","protected":false},"excerpt":{"rendered":"
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