Article ID: 6201, created on Mar 27, 2009, last review on Aug 12, 2014

  • Applies to:
  • Plesk 9.0 for Linux/Unix


arallels Plesk Panel version 9.0 is installed and Postfix MTA is used.

The following warning is shown in maillog:

Dec 18 18:28:45 plesk postfix/smtpd[6151]: warning: restriction reject_rbl_client requires domain name argument

What does it mean?


This is related to configuration of spam protection based on DNS blackhole list {Settings -> Mail Server Settings -> Switch on spam protection based on DNS blackhole lists}.

Even if the feature is disabled and list "DNS zones for DNSBL service" is empty, Parallels Plesk Panel adds line "smtpd_client_restrictions = reject_rbl_client" to mail header and the warning occurs.

This is configured in /etc/postfix/

~# grep smtpd_client_restrictions /etc/postfix/
smtpd_client_restrictions = reject_rbl_client

To resolve the problem you should add some DNS zone to the list "DNS zones for DNSBL service".
If you prefer leaving the feature disabled and the list empty you should reconfigure /etc/postfix/, remove entry "reject_rbl_client" near "smtpd_client_restrictions":

~# grep smtpd_client_restrictions /etc/postfix/
smtpd_client_restrictions =

This issue will be fixed in future update of Parallels Plesk Panel that is going to be released after version 9.2.

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