How to add a smart host in Office 365 (Exchange online)

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In order for outbound email from Microsoft Office 365 to be routed through a smart host, we need to create a new send connector in Office365 and point it to your smart host.
Create a new send connector in Office 365

  1. Log in to the Office 365 Exchange Admin Center (EAC)
  2. Select the Admin > Exchangemenu
  3. Select the Mail Flow > Connectors menu. Then, select Create a new Connector
  4. Set the mail flow scenario
    • Select Office 365 from the From: drop-down
    • Select Partner Organization from the To: drop-down
  5. Select Next
  6. Enter a name and description for the connector. You may also select the checkbox to make the connector active immediately
  7. Select Next
  8. Select the Only when email messages are sent to these domains option
    1. Select the plus (+) to add domains that should use this connector
    2. Enter a value of * (asterisk).This is a wildcard that will route all outbound emails through your smart host
  9. Select Next
  10. Select the Route email through these smart hosts option
    1. Select the plus (+) to add your smart
    2. Click the Save button
  11. Select Next
  12. Select the checkbox for Always use Transport Layer Security (TLS) to Secure the Connection (recommended)
  13. Select Issued by a trusted certificate authority (CA) from the list
  14. Select Next
  15. Add an email address of a recipient for a domain external to your organization, and select Validate to test

Note: If you did not choose to turn the connector on in Step 6, validation of the connector will fail. If your validation results show that the connection was successful, but the email failed to send because "The domain of the recipient is not configured as part of connector" - this may be due to the connector being disabled. Try enabling the connector and re-attempting the validation.

  1. Once Office365 has been successfully validated, select Save
  2. Update your SPF record accordingly

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