Office 365 User Provisioning Issue [Unable to create user’s mailbox]

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Issue Description

When a new user is created in On-Premise active directory which is then synced to Azure AD and a license has been assigned to the user, you get the error: This user’s on-premises mailbox hasn’t been migrated to Exchange Online. The Exchange Online mailbox will be available after migration is completed. Also, you see that the Mailbox is not created for this user in Exchange Online(EXO).

The Exchange Online mailbox will be available after migration is completed


a) Remove msExchMailboxGuid  attribute value from the On Premise Active Directory User.


b) Remove msExchRecipientDisplayType attribute value.


c) Remove msExchRecipientTypeDetails attribute value.


d) Move the user to an OU in Active Directory which is not getting synced to Azure Active Directory and run Delta Sync.

Start-ADSyncSyncCycle -PolicyType delta
Start-ADSyncSyncCycle -PolicyType delta

e) After the delta sync is complete, in couple of minutes you will see that the user is now deleted from Office365. You can find the user on Office 365 Admin Portal -> Users -> Deleted Users. This is the Recycle Bin where you can find the deleted users.

f) Now connect to MSOnline Powershell Module and Remove / Delete the user from RecycleBin. First use connect-msolservice to connect to MSOnline and then get the list of deleted users. Once you can find the deleted users UserPrincipalName, use Remove-msoluser command to delete the user permanently from recycle bin.

get-msoluser -ReturnDeletedUsers
Remove-MsolUser -UserPrincipalName -RemoveFromRecycleBin
get-msoluser -ReturnDeletedUsers
Remove-MsolUser -UserPrincipalName -RemoveFromRecycleBin

g) Now, Move the user back to the OU which is getting synced to Office365 and run delta sync again using command Start-AdSyncSyncCycle -policytype delta

Start-ADSyncSyncCycle -PolicyType delta

h) After the delta sync completes. Please check the user on office365 portal. Assign the license to the user again to create the mailbox. This time it should create the mailbox successfully.

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