Email delivery is failing with "451 4.3.0 <user@example.com>: Temporary lookup failure" error.

Solution Verified - Updated -

Issue

  • Postfix is configured to lookup users in ldap database but email delivery is failing with following error
Feb 18 16:53:53 host postfix/smtpd[15621]: > unknown[127.0.0.1]: 451 4.3.0 <user@example.com>: Temporary lookup failure

Environment

  • Red Hat Enterprise Linux 5.9
  • postfix-2.3.3-6.el5
  • openldap-servers-2.3.43-25.el5_8.1

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