Let us take a closer look at the postfix rbl override and the configurations associated with it. With the support of Server management support services at Bobcares will give you a  give a detailed note on the entire process.

What is RBL?

The RBL module supports comparing different message parts, such as sender IP addresses, URLs, Emails, Received header chains, SMTP data (such as HELO domain), and so on, to a variety of Runtime Black Lists (RBL) often given by specialized DNS zones.

Rspamd includes a set of RBL rules set to popular resources that are typically free for non-profit use (including fair usage policies). Now that we have gone through RBL let’s look at the postfix rbl override configuration.

Overriding (whitelisting) RBL blocks in Postfix on Plesk

If we enable the proxy SMTP and utilize the Realtime blacklist (RBL) on the Endian UTM Appliance to stop spam, we are likely to experience the following issue: Users occasionally claim that they are unable to receive emails from specific mailservers. Most of the time, this occurs because such mailservers were used to send spam and were thus blacklisted.

Configurations for Postfix RBL Override

Follow the steps given below for configurations on the rbl override.

1. Firstly we can use any text editor, and create the plain text files shown in the code given below:

   /etc/postfix/rbl override.
2. After that, add a comment line for adding the corresponding IPs, then add one IP address per line to the whitelist, followed by an OK. It will look something like this: # Whitelisting the following - customer domain.com - 11/15/20131.2.3.4 OK.
3. Run the following command from the /etc/postfix/ directory:postmap hash:rbl override
4. Make the following change to /etc/postfix/main.cf:smtpd_recipient_restrictions = permit_mynetworks, check_client_access pcre:/var/spool/postfix/plesk/no_relay.re, permit_sasl_authenticated, reject_unauth_destination Look like: smtpd_recipient_restrictions = permit_mynetworks, check_client_access hash:/etc/postfix/rbl_override, check_client_access pcre:/var/spool/postfix/plesk/no_relay.re, permit_sasl_authenticated, reject_unauth_destination
5. Now restart postfix; commonly “/etc/rc.d/init.d/postfix restart” on CentOS/RHEL/Scientific, or “postfix restart” on other distributions.

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Conclusion

To conclude we have now learned about the postfix rbl override and the various steps including the various necessary changes to configure it with the assistance of our Server management support services.