Cannot receive emails: Client host rejected: Service unavailable

Created:

2016-12-21 23:04:39 UTC

Modified:

2017-08-08 13:22:59 UTC

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Cannot receive emails: Client host rejected: Service unavailable

Applicable to:

  • Plesk Onyx for Linux

Symptoms

  1. Cannot receive emails. The following error may be found in /var/log/maillog :

    postfix/smtpd[5105]: NOQUEUE: reject: RCPT from unknown[203.0.113.2]: 450 4.7.1 <203.0.113.2>: Client host rejected: Service unavailable; from=<john.doe@example1.com> to=<jane.doe@example2.com> proto=ESMTP helo=<[203.0.113.2]>
    
  2. Warnings in /var/log/maillog :

    postfix/smtpd[5105]: warning: 192.0.2.2.dnsbl.example.tld: RBL lookup error: Host or domain name not found. Name service error for name=192.0.2.2.dnsbl.example.tld type=A: Host not found, try again
    
  3. The Postfix configuration parameter smtpd_recipient_restrictions is configured to use DNSBL service dnsbl.example.tld in /etc/postfix/main.cf file:

    # grep dnsbl.example.tld /etc/postfix/main.cf
    smtpd_recipient_restrictions = ...permit_dnsbl_client dnsbl.example.tld=192.0.2.2, 
    

Cause

The Postfix is configured to use non-existent DNSBL service.

Resolution

  1. Remove non-existent DNSBL service dnsbl.example.tld from Postfix configuration in /etc/postfix/main.cf :

    permit_dnsbl_client list.dnsbl.example.tld=192.0.2.2, permit_dnsbl_client list.dnsbl.tld=192.0.2.2,<\pre>
  2. Restart Postfix:

    # service postfix restart
    
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