SpamAssasin is the last weapon from our arsenal that we will use to keep spam away from our mail server.
Install needed packages:
apt-get install spamassassin spamc
We ned to add user that will be running spamassasin on our server:
groupadd spamd useradd -g spamd -s /bin/false spamd chown spamd:spamd -R /etc/spamassassin/
User is ready now we need configure SA to use it:
#vim /etc/default/spamassassin # 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 SPAMD_HOME="/home/spamd/" OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir /home/spamd/ -s /home/spamd/spamd.log" PIDFILE="/home/spamd/spamd.pid" CRON=1
Start SA:
service spamassassin start
Add SpamAssassin Support to postfix:
#vim /etc/postfix/master.cf
# on the bottom of file add:
spamassassin unix - n n - - pipe
user=spamd argv=/usr/bin/spamc -f -e
/usr/sbin/sendmail -oi -f ${sender} ${recipient}
# in every protocol we use (ex. smtps, submission) we should add this line below to forward mails to spamassasin:
-o content_filter=spamassassin
Restart postfix:
service postfix restart
We need to create rules for SA:
#/etc/spamassassin/local.cf rewrite_header Subject ***** SPAM _SCORE_ ***** report_safe 0 required_score 5.0 use_bayes 1 use_bayes_rules 1 bayes_auto_learn 1 skip_rbl_checks 0 use_razor2 0 use_dcc 0 use_pyzor 0 #Adjust scores for SPF FAIL score SPF_FAIL 4.0 score SPF_HELO_FAIL 4.0 score SPF_HELO_SOFTFAIL 3.0 score SPF_SOFTFAIL 3.0 #adjust DKIM scores score DKIM_ADSP_ALL 3.0 score DKIM_ADSP_DISCARD 10.0 score DKIM_ADSP_NXDOMAIN 3.0
Restart service to be sure we use newest rules:
service spamassassin restart
To test spamassasin we can send mail from external mail server to our server and check header to see if spamassasin added his header with scoring.
Update 05/11/2016:
I notice that spamassassin throw error in syslog
warn: config: failed to parse line, skipping, in "/etc/spamassassin/local.cf": use_dcc 0
This can be fix easily by commenting out use_dcc line or adding dcc and not use it (pointless)
Rest post related to this topic:
Postfix i Dovecot – perfect duo for mail server
Fight against spam part 1 – Postfix SPF
Fight against spam part 2 – Postfix DKIM
Fight against spam part 3 – Postfix DMARC
Fight against spam part 5 – Dovecot Sieve