Setup a Spam Filter with SpamAssasin with Postfix

If you receive a lot of spams here is a quick solution to filter spams using SpamAssasin and Postfix. Also spamd will be used (which is include within SpamAssasin). There are other implementations that we will cover in other tutorials. Step 1. Install Postfix ----------------------------- We will install Postfix from Ports: cd /usr/ports/mail/postfix make install If you want to use Postfix with MySQL, you must check MySQL before compilation, also you may want to check Dovecot, to use Dovecot SASL authentication method. We recommend you dovecot over cyrus-imap. After installation, configure postfix by editing: /usr/local/etc/postfix/master.cf and /usr/local/etc/postfix/main.cf # -------------------- main.cf ----------------------------------------- queue_directory = /var/spool/postfix command_directory = /usr/local/sbin daemon_directory = /usr/local/libexec/postfix mail_owner = postfix unknown_local_recipient_reject_code = 550 mynetworks_style = host debug_peer_level = 2 debugger_command =          PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin          xxgdb $daemon_directory/$process_name $process_id & sleep 5 sendmail_path = /usr/local/sbin/sendmail mailq_path = /usr/local/bin/mailq setgid_group = maildrop html_directory = no manpage_directory = /usr/local/man sample_directory = /usr/local/etc/postfix readme_directory = no #smtpd_recipient_restrictions = check_relay_domains, permit mydomain = example.com myhostname = firewall.$mydomain myorigin = $myhostname mydestination = $myhostname, localhost,$mydomain mynetworks = 10.0.0.5/32 mynetworks_style = subnet # --------- end of file main.cf -------------------- Also add the following line to /etc/rc.conf postfix_enable="YES" Notes: Note1 -------- Don't forget to setup in main.cf the variable: mydestination = $myhostname, localhost,$mydomain If you forget to do that, you will get rely denied error, and emails that comes to your domain name will be rejected. If you have many domains you can use transport_maps variable: mydestination = $mydomain, $myhostname, $transport_maps, localhost Transport maps can be also used from within mysql (for large mail servers with postfix compiled and configured with virtual users and MySQL support. If you are interested there is a tutorial on that topic on our website. Note2 -------- Make sure you either add your IP in main.cf with your mynetworks variable or setup smtp server with authentication and allow your username to use SMTP with authentication. mynetworks = 10.0.0.2/32 Step 2. Install SpamAssasin --------------------------------------- cd /usr/ports/mail/p5-Mail-SpamAssassin make install Step 3. Configure SpamAssasin -------------------------------------------- After compilation and installation of SpamAssasin (which is written in Perl) from ports, as described in Step 2, create a config file for spamassasin: touch /usr/local/etc/mail/spamassasin/local.cf with the following content: # ---------- local.cf -------------- rewrite_header Subject *****SPAM***** # trusted_networks 10.0.0. # lock_method flock # use_bayes 1 # bayes_auto_learn 1 required_score 5.0 report_safe     1 whitelist_from This email address is being protected from spam bots, you need Javascript enabled to view it # --------- end of local.cf If you want to catch more spams, but also you will have more false positive, lower required_score. Higher score will catch less spams. Step 4. Start spamd ---------------------------- Edit /usr/local/etc/rc.d/sa-spamd and change spamd_enable to "YES". Then, start spamd: /usr/local/etc/rc.d/sa-spamd start Step 5. Edit master.cf and add support for spamassasin ------------------------------------------------------------------- Edit /usr/local/etc/postfix/master.cf, replace line: smtp      inet  n       -       n       -       -       smtpd with: smtp      inet  n       -       -       -       -       smtpd         -o content_filter=spamassassin And then add the following lines to master.cf. spamassassin unix -     n       n       -       -       pipe         user=spamd argv=/usr/local/bin/spamc -f -e         /usr/sbin/sendmail -oi -f ${sender} ${recipient} Step 6. Restart postfix and test the setup --------------------------------------------------------- /usr/local/etc/rc.d/postfix restart

 

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