Knowledgebase: Inbound Mail Flow
Email bounces with the message 'Address lookup failed'
Posted by Riaan Kok, Last modified by David Szoke on 19 January 2018 07:09 PM

This error occurs when the customer in question has the 'Enable email relay' option switched on and someone tries to send email to a recipient address that is not registered with Proofpoint Essentials and the recipient domain is configured in Proofpoint Essentials with an SMTP Destination server that refuses to accept address verification probes from Proofpoint Essentials.

We see this error occur when all the below conditions are met.

  • Proofpoint Essentials customer has the domain launched and ready to use, i.e. the "Enable email relay is set to Yes".
  • An email is sent to a non-registered address for the said domain.
  • The domain is configured properly in the Proofpoint Essentials interface, but the mail server refuses to accept address verification probes.


For some more information, refer to the knowledgebase article on [Setup Step 1]

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