How to setup the anti-spam & anti-virus

Prerequisite: postfix should be up and running


1. installation

   sudo apt-get install amavisd-new spamassassin clamav-daemon
   sudo apt-get install dkim-filter python-policyd-spf
   sudo apt-get install pyzor razor
   sudo apt-get install arj cabextract cpio lha nomarch pax rar unrar unzip zip zoo

2. configuration

   a) ClamAV (sudo nano /etc/clamav)  - the default is fine
  
          a.1) Add clamav user to the amavis group in order for Amavisd-new to have the appropriate access to scan files
   
               sudo adduser clamav amavis
    
   b) Spamassassin            
      
      b.1)  sudo nano /etc/default/spamassassin

            ENABLED=1   #activate the Spamassassin daemon

      
      b.2) sudo /etc/init.d/spamassassin start


   c) Amavisd-new

      c.1) activate spam and antivirus detection in Amavisd-new 

          sudo nano /etc/amavis/conf.d/15-content_filter_mode
 

          @bypass_virus_checks_maps = (
              \%bypass_virus_checks, \@bypass_virus_checks_acl, \$bypass_virus_checks_re);


          @bypass_spam_checks_maps = (
             \%bypass_spam_checks, \@bypass_spam_checks_acl, \$bypass_spam_checks_re);

      c.2) Bouncing spam is the default, you may discard it as bellow

          sudo nano /etc/amavis/conf.d/20-debian_defaults    

          $final_spam_destiny       = D_DISCARD;

          
      c.3) If host name is different from the domain's MX record you may need to 
           manually set the $myhostname option. 
             Also, if the server receives mail for multiple domains 
          the @local_domains_acl option will need to be customized.  


          sudo nano  /etc/amavis/conf.d/50-user   

          $myhostname = 'mail.example.com';
 
          @local_domains_acl = ( "example.com", "example.org" );
          
          
      c.4) sudo /etc/init.d/amavis restart

          

    d) DKIM Whitelist (once a domain has been added to the Whitelist the message 
       will not receive any anti-virus or spam filtering.)


       /etc/amavis/conf.d/40-policy_banks
       
    
    e) Postfix

       sudo postconf -e 'content_filter = smtp-amavis:[127.0.0.1]:10024'


    f) sudo nano /etc/postfix/master.cf  


      (Note: add the following at the end. Don't leave space before the line "smtp-amavis" and "127.0.0.1:10025")
          
         
     smtp-amavis     unix    -       -       -       -       2       smtp
        -o smtp_data_done_timeout=1200
        -o smtp_send_xforward_command=yes
        -o disable_dns_lookups=yes
        -o max_use=20

     127.0.0.1:10025 inet    n       -       -       -       -       smtpd
        -o content_filter=
        -o local_recipient_maps=
        -o relay_recipient_maps=
        -o smtpd_restriction_classes=
        -o smtpd_delay_reject=no
        -o smtpd_client_restrictions=permit_mynetworks,reject
        -o smtpd_helo_restrictions=
        -o smtpd_sender_restrictions=
        -o smtpd_recipient_restrictions=permit_mynetworks,reject
        -o smtpd_data_restrictions=reject_unauth_pipelining
        -o smtpd_end_of_data_restrictions=
        -o mynetworks=127.0.0.0/8
        -o smtpd_error_sleep_time=0
        -o smtpd_soft_error_limit=1001
        -o smtpd_hard_error_limit=1000
        -o smtpd_client_connection_count_limit=0
        -o smtpd_client_connection_rate_limit=0
        -o receive_override_options=no_header_body_checks,no_unknown_recipient_checks


         (Note: Also add the following two lines immediately below the "pickup" transport service: )

         -o content_filter=
         -o receive_override_options=no_header_body_checks


3. test

   a) Amavisd-new SMTP is listening    (directly in Ubuntu system)
      
      telnet localhost 10024
      Trying 127.0.0.1...
      Connected to localhost.
      Escape character is '^]'.
      220 [127.0.0.1] ESMTP amavisd-new service ready
      ^]
       
   b) In the Header of messages you should see: 

      X-Spam-Level: 
      X-Virus-Scanned: Debian amavisd-new at example.com
      X-Spam-Status: No, hits=-2.3 tagged_above=-1000.0 required=5.0 tests=AWL, BAYES_00
      X-Spam-Level: 






In addtion: 

1) to get the stuck message:

postfix reload
requeue the stuck messages: 
postsuper -r ALL
wait for the messages to requeue (about a minute and a half should be good)
postfix reload

2) to display the config of /etc/postfix/main.cf)

postconf -n