Why does sendmail wait to send deferred messages, and how can it deliver the messages faster?

Solution Verified - Updated -


  • In a number of conditions, such as a loss of connectivity to a wide area network, a DNS resolution issue, a downtime of the relay host (usually defined with the SMART_HOST directive in the sendmail configuration files), sendmail will not be able to deliver messages.
  • Those messages are then queued as deferred messages.
  • Once working production conditions are restored, messages are not delivered immediately.
  • The E-mail service can be impacted by the resulting delay.


  • Red Hat Enterprise Linux (RHEL) 4 or 5
  • sendmail

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