Centos 7 | Postfix + Postgrey and other SPAM evasive actions

[paknet]

Say bye bye to huge amount of SPAM messages with this simple to install daemon.


Install Postgrey:

Code:

yum install postgrey

edit this file

Code:

vi /etc/sysconfig/postgrey

and change this line from

Code:

POSTGREY_OPTS="--delay=60"

to

Code:

POSTGREY_OPTS="--delay=300"

Start the service and make sure that daemon is automatically started after reboot:

Code:

systemctl start postgrey systemctl enable postgrey

OK. Now we need to tell Postfix to start using Postgrey and also set some other SPAM evasive actions

Edit the file:

Code:

vi /etc/postfix/main.cf

… find this “block”

Code:

# rules restrictions smtpd_client_restrictions = smtpd_helo_restrictions = smtpd_sender_restrictions = smtpd_recipient_restrictions = permit_sasl_authenticated,        permit_mynetworks,        reject_unauth_destination,        reject_non_fqdn_sender,        reject_non_fqdn_recipient,        reject_unknown_recipient_domain # uncomment for realtime black list checks. (Warn: will also reject false positive) #       ,reject_rbl_client zen.spamhaus.org #       ,reject_rbl_client bl.spamcop.net #       ,reject_rbl_client dnsbl.sorbs.net

… and replace it with this one:

Code:

# rules restrictions smtpd_client_restrictions =        permit_mynetworks,        permit_sasl_authenticated smtpd_sender_restrictions =        permit_sasl_authenticated,        permit_mynetworks,        reject_non_fqdn_sender,        reject_unknown_sender_domain,        permit smtpd_recipient_restrictions =        permit_mynetworks,        permit_sasl_authenticated,        check_policy_service unix:/var/spool/postfix/postgrey/socket,        reject_invalid_hostname,        reject_unauth_destination,        reject_non_fqdn_sender,        reject_non_fqdn_recipient,        reject_unknown_recipient_domain,        reject_unauth_pipelining,        reject_unknown_sender_domain,        reject_unknown_recipient_domain, # uncomment for realtime black list checks        reject_rbl_client sbl-xbl.spamhaus.org, #       reject_rbl_client multi.uribl.com, ### Too many requests - payable service        reject_rbl_client dsn.rfc-ignorant.org,        reject_rbl_client dul.dnsbl.sorbs.net,        reject_rbl_client bl.spamcop.net, #       reject_rbl_client dnsbl.sorbs.net, # Emails from yahoo are blocked with this one        reject_rbl_client cbl.abuseat.org,        reject_rbl_client ix.dnsbl.manitu.net,        reject_rbl_client combined.rbl.msrbl.net,        reject_rbl_client rabl.nuclearelephant.com,        permit

below that block find this line:

Code:

smtpd_data_restrictions = reject_unauth_pipelining

… and replace it with:

Code:

smtpd_data_restrictions =        reject_unauth_pipelining,        permit_mynetworks,        permit_sasl_authenticated

One last thing…
find the line:

Code:

message_size_limit = 20480000

… and paste the following before that line:

Code:

# Try to resend mail after 15 min transport_retry_time = 15m # More anti-spam checks smtpd_delay_reject = yes smtpd_helo_restrictions =    permit_mynetworks,    permit_sasl_authenticated,    reject_non_fqdn_hostname,    reject_invalid_hostname,    reject_unknown_helo_hostname,    permit

Save and close the file and restart the Postfix

Code:

systemctl restart postfix

Just to make sure that Postgray is working, check the maillog:

Code:

tail -f /var/log/maillog

… and send a mail from external (non hosted) domain. Note: google and bunch of others are Whitelisted by default.

You should see a line like this:

Code:

Feb 00 00:00:00 host postgrey[122947]: action=greylist, reason=new, client_name=mail.domain.com

Thats it! You’ve dramatically reduced the amount of SPAM messages =)

[Qtech]

Hello have you installed RRDtool with this as well. If so would you care to show us a guide.

[Qtech]

Thank you, thank you, thank you.

[wormsunited]

I made all steps, going to check if they work, even so huge contribution to the community, thanks a million times!

[wormsunited]

Hi there, by far this made a reduction of 80% on the spam indeed. Great post highly recommended.