Article ID: 124726, created on Mar 4, 2015, last review on Mar 4, 2015

  • Applies to:
  • Plesk 11.0 for Linux
  • Plesk 11.5 for Linux
  • Plesk 12.0 for Windows


Mail from specific servers gets rejected at Plesk Panel server. In mail client following message appears:

An error occurred sending mail: Unable to establish a secure link with SMTP server using STARTTLS since it doesn't advertise that feature. Switch off STARTTLS for that server or contact your service provider.

In /usr/local/psa/var/log/maillog file there are following messages:

localhost postfix/smtpd[17588]: NOQUEUE: reject: RCPT from mail.server: 554 5.7.1 Service unavailable; Client host [] blocked using zen.dnsbl;; from=<mail@domain2.tld> to=<mail@domain1.tld> proto=ESMTP helo=<mail.server>
localhost /usr/lib64/plesk-9.0/psa-pc-remote[21418]: Message aborted.


The IP-address of sending server is listed in spam block lists.


Either delete blocking spam list server from Plesk Panel at Tools & Settings > Mail Server Settings > Switch on spam protection based on DNS blackhole lists > DNS zones for DNSBL service or check more information in the URL provided at maillog. In current case it is

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