Postgrey

• "Postgrey is a Postfix policy server implementing greylisting" -- [web site]
• Responding to this SAC ticket

Dependencies

It uses the BerkeleyDB, and other, perl modules. Perl's -MCPAN install option was failing on building BerkeleyDB module, so RPMs were gathered from searches to pbone.net for RHEL4. Then they were installed like this:

sudo rpm -i perl-BerkeleyDB-0.33-1.el4.rf.i386.rpm perl-IO-Multiplex-1.09-3.el4.pp.noarch.rpm  perl-Net-Server-0.97-2.el4.pp.noarch.rpm postgrey-1.31-1.el4.rf.noarch.rpm

Install & Config

• For more install instructions see the manual (man) pages for postgrey on the server.
• Edit /etc/postfix/main.cf file adding:

  smtpd_recipient_restrictions = permit_mynetworks,
       permit_sasl_authenticated,
       reject_invalid_hostname,
       reject_non_fqdn_hostname,
       reject_non_fqdn_sender,
       reject_unauth_destination,
       reject_unknown_recipient_domain,
       reject_unauth_pipelining,
       reject_unauth_destination,
       #reject_rbl_client list.dsbl.org,
       #reject_rbl_client sbl.spamhaus.org,
       #reject_rbl_client zen.spamhaus.org,
       #reject_rbl_client lists.spam.sux.com,
       check_policy_service unix:postgrey/socket,
       permit

 Note:  The reject_rbl_client lines are for real time blacklisting and have been
        commented because this is most likely more aggressive spam filtering 
        than we require.  I put them there as examples of additional filtering that
        could be done. 

• start postgrey daemon/service

   $ sudo /sbin/service postgrey start

• set postgrey to start on boot

   $ sudo /sbin/chkconfig --level 2345 postgrey

• restart postfix daemon/service

   $ sudo /sbin/service postfix restart

• you can watch the greylisting in : /var/log/maillog

   $ sudo tail -f /var/log/maillog |grep Greylist

To revert back to original (pre greylisting) config

Edit /etc/postfix/main.cf and comment out lines 222 to 236

   smtpd_recipient_restrictions = permit_mynetworks,
       permit_sasl_authenticated,
       reject_invalid_hostname,
       reject_non_fqdn_hostname,
       reject_non_fqdn_sender,
       reject_unauth_destination,
       reject_unknown_recipient_domain,
       reject_unauth_pipelining,
       reject_unauth_destination,
       #reject_rbl_client list.dsbl.org,
       #reject_rbl_client sbl.spamhaus.org,
       #reject_rbl_client zen.spamhaus.org,
       #reject_rbl_client lists.spam.sux.com,
       check_policy_service unix:postgrey/socket,
       permit

Restart postfix

$ systemctl restart postfix

References

• http://www.howtoforge.com/greylisting_postfix_postgrey