Mailbox User migration fails from On Premise to Office 365

Doing migrations there is always the odd one of two users who fail to migrate for various reasons one of the most common ones I have found is when a User’s AD account does not have inherit permissions applied which causes the users email to be in limbo as it has migrated successfully to the cloud but the AD atrributes were not updated by the process. Below I will show you the steps in this scenario!

With the base platform as Exchange 2003 an hybrid Exchange 2010 SP2 RU2. (Although I have not tested this for Exchange 2007 there is no reason why this does not also work)

  1. Open AD Users & Computers > Ensure that advanced features is Checked (Choose View in the MMC and select “Advanced Features”
  2. Find the users Account
  3. Right click the account and choose properties
  4. Select the “Security Tab” and click “Advanced”
  5. Select the “Allow inheritable…” check box
  6. Wait for 15 minutes or force replication for the changes to be applied
  7. Jot down or copy the ON-PREMISE objects “LegacyExchangeDN” using ADSIedit.mmc (NOTE THIS IS VERY IMPORTANT TO DO SO)
  8. Mail disable the on-prem object using the 2003 Exchange MMC
  9. Remove any email attributes that are left so the AD account has no association with Exchange
  10. Re create the email attributes as a contact (so no mailbox) in the format of
  11. Add the old LegacyExchangeDN to the account as an X500 address
  12. Add in the cloud objects LegacyExchangeDN also as an X500 address (This can be obtained through PowerShell connecting to the hosted service and running get-mailbox -identity | fl)
  13. Clear the “Automatically update e-mail addresses based on e-mail address policy” check box on the Exchange attributes after this has applied the users email addresses.
  14. Set the users on premise primary SMTP as
  15. Re run DirSync after you have waiting for replication to happen again
  16. Then viola the user can open up their mailbox and be re directed to the cloud as long as the autodiscover service has been configured correctly.

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