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rtpcrew's avatar
rtpcrew
Copper Contributor
Feb 25, 2025

Arbitration Mailboxes not available

I have an environment with an Exchange 2013 (15.00.1497.048) and an Exchange 2019 CU14 server installed. The new 2019 server appears to be fully operational with the exception of the system mailboxes, which means I cannot migrate the mailboxes off the 2013 server.

What I have tried to resolve this issue:

  1. Re-run /PrepareAD - This did create the AD accounts; however, the system mailboxes were not created and when attempting to enable them getting the following error:
    "The user's Active Directory account must be logon-disabled for linked, shared, or resource mailbox."
  2. Checked for disabled or soft-deleted mailboxes - none that match the GUIDs for the system mailboxes
  3. Deleted the system accounts from Active Directory and re-ran /PrepareAD. It ran successfully and created the AD accounts; however, still getting the same error when attempting to enable the mailboxes.

Looking for any insight into how to resolve this issue.

2013
2019
Exchange Server
hybrid
office 365
  • Dan_Snape's avatar
    Dan_Snape
    Steel Contributor
    Feb 25, 2025

    PrepareAd creates the AD accounts and the mailboxes. These are "hidden" so you won't see them in the GUI and you won't see them in PowerShell unless you specify that you are looking for arbitration mailboxes. You definitely shouldn't need to enable them as mailboxes. All you need to do is migrate them to a mailbox database on the new server

    Set-ADServerSettings -ViewEntireForest $True

    Get-Mailbox -Arbitration | New-MoveRequest -TargetDatabase <Ex2019DatabaseName>

     

    If you do need to recreate them, the steps are outlined here:

    https://learn.microsoft.com/en-us/exchange/architecture/mailbox-servers/recreate-arbitration-mailboxes?view=exchserver-2019

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