Sending mail via Sendmail gives error in maillog "Name server: host name lookup failure"

Solution Verified - Updated -


  • Trying to send email gives error:
Jun 20 16:28:21 i5981dlg11 sendmail[23064]: q5KJV9nd010876: to=<>, ctladdr=<> (0/0), delay=00:57:12, xdelay=00:00:00, mailer=relay, pri=210350,, dsn=4.0.0, stat=Deferred: Name server: host name lookup failure
  • Here is configured as smart host.


  • Red Hat Enterprise Linux 5
  • Red Hat Enterprise Linux 6

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