Re-create missing arbitration mailboxes

Exchange 2016 CU8 or later contains seven special system mailboxes known as arbitration mailboxes. Arbitration mailboxes are used for storing different types of system data and for managing messaging approval workflow. The following table lists each type of arbitration mailbox and their responsibilities.

If you need to re-create one of more of these arbitration mailboxes, use the instructions in this article.

What do you need to know before you begin?

• Estimated time to complete: 10 minutes per procedure.

• You need to be assigned permissions before you can perform these procedures. To see what permissions you need, see the "Recipient Provisioning Permissions" section in the Recipients Permissions topic.

• To run Setup.exe /PrepareAD, your account needs to be a member of the Enterprise Admins security group.

• The computer that you use to run Setup.exe /PrepareAD requires access to Setup.exe in the Exchange installation files:

  1. Use your most recently downloaded copy of the Exchange ISO image file, or download an updated copy from Updates for Exchange Server.
  2. In File Explorer, right-click on the Exchange ISO image file and then select Mount. Note the virtual DVD drive letter that's assigned.
  3. Open a Windows Command Prompt window. For example:
     • Press the Windows key + 'R' to open the Run dialog, type cmd.exe, and then press OK.
     • Press Start. In the Search box, type Command Prompt, then in the list of results, select Command Prompt.

• For more information about opening the Exchange Management Shell, see Open the Exchange Management Shell.

• For more information about running Exchange Setup in unattended mode, see Use unattended mode in Exchange Setup.

Re-create an arbitration mailbox

Use the following instructions to re-create a particular type of arbitration mailbox.

Re-create the Microsoft Exchange Federation Mailbox

To re-create the arbitration mailbox FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042, run the following commands:

1. If the mailbox is missing, run the following command from a Windows Command Prompt window:

   <Virtual DVD drive letter>:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

   For example:

   E:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

2. In the Exchange Management Shell, run the following command:

   Enable-Mailbox -Identity "FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042" -Arbitration
   

Re-create the Microsoft Exchange Migration mailbox

To re-create the arbitration mailbox Migration.8f3e7716-2011-43e4-96b1-aba62d229136, run the following commands:

1. If the mailbox is missing, run the following command from a Windows Command Prompt window:

   <Virtual DVD drive letter>:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

   For example:

   E:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

2. In the Exchange Management shell, run the following command:

   Enable-Mailbox -Identity "Migration.8f3e7716-2011-43e4-96b1-aba62d229136" -Arbitration
   

3. In the Exchange Management Shell, set the Persisted Capabilities (msExchCapabilityIdentifiers) for the mailbox by running the following command:

   Set-Mailbox -Identity "Migration.8f3e7716-2011-43e4-96b1-aba62d229136" -Arbitration -Management $true -Force
   

Re-create the Microsoft Exchange Approval Assistant mailbox

To re-create the arbitration mailbox SystemMailbox{1f05a927-XXXX-XXXX-XXXX-XXXXXXXXXXXX}, run the following commands:

1. If the mailbox is missing, run the following command from a Windows Command Prompt window:

   <Virtual DVD drive letter>:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

   For example:

   E:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

2. In the Exchange Management Shell, run the following command:

   Get-User -ResultSize Unlimited | where {$_.Name -like "SystemMailbox{1f05a927*"} | Enable-Mailbox -Arbitration
   

Re-create the Microsoft Exchange organization mailbox for OABs

To re-create the arbitration mailbox SystemMailbox{bb558c35-97f1-4cb9-8ff7-d53741dc928c}, run the following commands:

1. If the mailbox is missing, run the following command from a Windows Command Prompt window:

   <Virtual DVD drive letter>:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

   For example:

   E:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

2. In the Exchange Management Shell, run the following command:

   Enable-Mailbox -Identity "SystemMailbox{bb558c35-97f1-4cb9-8ff7-d53741dc928c}" -Arbitration
   

3. In the Exchange Management Shell, set the Persisted Capabilities (msExchCapabilityIdentifiers) for the mailbox by running the following command:

   Get-Mailbox "SystemMailbox{bb558c35-97f1-4cb9-8ff7-d53741dc928c}" -Arbitration | Set-Mailbox -Arbitration -UMGrammar $true -OABGen $true -GMGen $true -ClientExtensions $true -MessageTracking $true -PstProvider $true -MaxSendSize 1GB -Force
   

4. In the Exchange Management Shell, add the required capabilities to the mailbox by running the following commands:

   $OABMBX = Get-Mailbox "SystemMailbox{bb558c35-97f1-4cb9-8ff7-d53741dc928c}" -Arbitration; Set-ADUser $OABMBX.SamAccountName -Add @{"msExchCapabilityIdentifiers"="40","42","43","44","47","51","52","46"}
   

Re-create the Microsoft Exchange Discovery system mailbox

To re-create the arbitration mailbox SystemMailbox{e0dc1c29-89c3-4034-b678-e6c29d823ed9}, run the following commands:

1. If the mailbox is missing, run the following command from a Windows Command Prompt window:

   <Virtual DVD drive letter>:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

   For example:

   E:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

2. In the Exchange Management shell, run the following command:

   Enable-Mailbox -Identity "SystemMailbox{e0dc1c29-89c3-4034-b678-e6c29d823ed9}" -Arbitration
   

3. In the Exchange Management Shell, set the Persisted Capabilities (msExchCapabilityIdentifiers) for the mailbox by running the following command:

   Set-Mailbox -Identity "SystemMailbox{e0dc1c29-89c3-4034-b678-e6c29d823ed9}" -Arbitration -UMDataStorage $true -Force
   

Re-create the Microsoft Exchange 2016 CU8 and later system mailboxes

To re-create the arbitration mailbox SystemMailbox{D0E409A0-AF9B-4720-92FE-AAC869B0D201} and SystemMailbox{2CE34405-31BE-455D-89D7-A7C7DA7A0DAA}, run the following commands:

1. If the mailboxes are missing, run the following command from a Windows Command Prompt window:

   <Virtual DVD drive letter>:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

   For example:

   E:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD
   

2. In the Exchange Management shell, run the following command:

   Enable-Mailbox -Identity "SystemMailbox{D0E409A0-AF9B-4720-92FE-AAC869B0D201}" -Arbitration
   Enable-Mailbox -Identity "SystemMailbox{2CE34405-31BE-455D-89D7-A7C7DA7A0DAA}" -Arbitration 
   

3. In the Exchange Management Shell, configure some mailbox properties and set the Persisted Capabilities (msExchCapabilityIdentifiers) for the mailbox by running the following command:

   Set-Mailbox -Identity 'SystemMailbox{2CE34405-31BE-455D-89D7-A7C7DA7A0DAA}' -Arbitration -DisplayName 'Microsoft Exchange' -RequireSenderAuthenticationEnabled $false -UseDatabaseQuotaDefaults $false -SCLDeleteEnabled $false -SCLJunkEnabled $false -SCLQuarantineEnabled $false -SCLRejectEnabled $false -HiddenFromAddressListsEnabled $true -Force
   
   $ShardMBX = Get-Mailbox -Identity 'SystemMailbox{2CE34405-31BE-455D-89D7-A7C7DA7A0DAA}' -Arbitration
   Set-ADUser $ShardMBX.SamAccountName -Add @{ msExchCapabilityIdentifiers = 66 }
   

How do you know this worked?

To verify that you've successfully re-created the arbitration mailbox, set the search scope to search the entire Active Directory forest, and then use the Get-Mailbox cmdlet with the Arbitration switch to retrieve system mailboxes.

Set-ADServerSettings -ViewEntireForest $true; Get-Mailbox -Arbitration | Format-Table Name,DisplayName

View the results of the command to verify that appropriate system mailbox, either by Name or Display Name from the above table, has been re-created.