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How can I set msExchMailboxGUID attribute to null?

Last Update: 7/21/2017 11:31 AM
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How can I set msExchMailboxGUID attribute to null?


This can be set within Synchronization Rules Editor.


  • This is not supported, if you have performed a directory synchronization using DirSync.
  • It is supported, if performing a directory synchronization using AAD Sync, or AAD Connect.
  • For more details on the correct order of steps to follow for directory synchronization, refer to KB004336.




Run the Synchronization Rules Editor as an administrator.



Click on In from AD – User Exchange to edit the Inbound Rule Type.



Select Transformations. Find the msExchMailboxGuid attribute.

Change it to the following:

Expression - msExchMailboxGuid - NULL - Checkmark Apply Once - Click on Update



Enable AADSync or AAD Connect and perform a full synchronization.

Now users may be assigned an Exchange Online license, and MigrationWiz may be used to migrate their mailboxes to Office 365.