Recreate and enable missing arbitration user accounts and mailboxes in Exchange Server 2010

I was asked a question today regarding missing arbitration user accounts and mailboxes. The customer had for some reason, lost or deleted the system mailboxes and did not know how to get them back. Here is how you do it if you end up in the same situation.

There are a number of accounts that you might have to recreate. All these can be found in the “Users” OU in Active Directory. They should look something like this:

• FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042
• SystemMailbox{1f05a927-af78-475a-aba4-fc281398eb54}
• SystemMailbox{e0dc1c29-89c3-4034-b678-e6c29d823ed9}

The GUIDs in the name of the accounts in your environment will differ from my example since these are automatically generated.To see if there are any arbitration mailboxes present you can run the following command. In my example, all of the arbitration mailboxes are missing.

Get-Mailbox –Arbitration

Active Directory Accounts

This one is simple, you will have to use the Exchange 2010 setup and run PrepareAD and the process will add the missing accounts again. Make sure that you run the command with the latest installed version of Exchange. If you have installed SP1 use the SP1 installation media. Also, make sure that you use an elevated command prompt when executing the command.

setup.com /PrepareAD

When this is complete you will have the recreated user accounts in the “Users” OU in Active Directory. Leave ADUC open since we need to get the names for the accounts in the next step.

Mailboxes

Next we move on to the mailboxes for the newly recreated users. This to is quite simple, all you have to do is to enable the mailboxes for the Active Directory Users.

Use the following command to enable the mailboxes:

Enable-Mailbox –Arbitration –Identity “FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042”

Enable-Mailbox –Arbitration –Identity “SystemMailbox{1f05a927-8668-4003-adad-9b80758e86db}”

Enable-Mailbox –Arbitration –Identity “SystemMailbox{e0dc1c29-89c3-4034-b678-e6c29d823ed9}”

You should also set the correct display name for one of the mailboxes using this commands:

Set-Mailbox –Arbitration –Identity “SystemMailbox{e0dc1c29-89c3-4034-b678-e6c29d823ed9}” –DisplayName “Microsoft Exchange”

It can be a bit tricky to determine which one of the SystemMailbox mailboxes that should have the display name “Microsoft Exchange”. If you look at the GUID for this user you can see that is starts with “e0dc1c29”, that is what you should be looking for.

You should also reset the quota for the “FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042” mailbox. This can be done using the following command:

Set-Mailbox –Arbitration –Identity “FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042” –ProhibitSendQuota 1MB

Once you have finished these commands you should be all set. If you want to make sure that the commands really worked you can list the arbitration mailboxes by using the following command:

Get-Mailbox –Arbitration

Please do not hesitate to let me know if you got any further questions or thoughts, thanks for reading!