Active Directory Accounts not syncing to Azure AD

Making the move to Azure AD and Office 365? Having a problem with active directory accounts not syncing to Azure AD? Of course, there could be a few reasons for this but one of them may be because you still have an on-premise Exchange environment and some of your on-premise active directory accounts may have a Linked Mailboxes attached to their AD accounts instead of User Mailboxes. Linked mailboxes cannot be migrated to Office 365.

Let’s back up just a little bit to give you some context. During the process of migrating our users to Office 365, we started to notice that several accounts were not syncing to Azure Active Directory, therefore we could not activate those users for Office 365. After comparing users that were synced with users not being synced, I noticed one difference. The users not being synced all had Linked Mailboxes in Exchange. These were older accounts that had been around for a while and were part of a domain migration years ago thus the reason they all had “linked mailboxes” instead of “user mailboxes”.

In order to resolve the syncing issue, all I needed to do is to convert the linked mailbox to a user mailbox.

Although there are several articles stating that converting Linked Mailboxes to User Mailboxes should cause no adverse affects, PLEASE try this is a test lab or with a test account before doing this in your PRODUCTION environment. You’ve been warned.

  • Log on to your Exchange Server and open the PowerShell Console as administrator
  • Run the following PowerShell command to view one of the accounts NOT syncing:
    • get-user -Identity <account> | fl LinkedMasterAccount
    • you will receive a display showing the account is linked (see below)
      LinkedMasterAccount : domain\<account>
  • Set it back to Null using the following PowerShell command:
    • set-user -Identity <account> LinkedMasterAccount $null

If you have a bunch of accounts, you can easily create a PowerShell script to parse through a file containing all your linked mailbox accounts and set them back to null in no time at all!


George Almeida

Welcome to my little corner of the blogosphere. I'm an Information Technology manager for a Fortune 500 company. I specialize in Windows operating systems, applications, servers, storage, networks and also have a technical background on the IBM iSeries platform. My only purpose for this blog is the hope that it helps someone, someday, somewhere. Any meager proceeds derived from our sponsors will be donated to charity.

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