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How to troubleshoot Email Delivery Failure Outbound

Written April 2018. Microsoft changes these admin screens often, so the screenshots below may not match what you see today. The sequence of steps is usually still correct — if something looks wrong, tell us and we'll update it.

Time to Execute: 30m

Let take an example here of the id user@contoso.com sends an email to user2@contoso.com

But the sender is unable to send the mail.

The following will be the troubleshooting steps.

  • Check the recipient address to which the mail is supposed to be sent is correct.
  • Check the sender has properly setup the proxy addresses for email alias.

  • Check the sender has a user properly setup for the Exchange and is given the required product licenses.

  • Check the senders outlook profile has configured accurately.
  • Check the Exchange mail flow rules

  • To have a clear look what's exactly happening with the mail, you may use the Message Traces in Office 365 Security and Compliance Center.

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