Saturday, July 3, 2010

Arbitration Mailboxes and Moderated Email – Part 1

As more and more admins install Exchange 2010, they are quickly faced with an error message.  What is the first thing that admins want to do when configuring the mailbox role?…create production mailbox databases and delete the default database that Exchange installed.  Well, Exchange 2010 installs a few special mailboxes on the first database.  Oh yeah…and you probably won’t even realize that they are there since they do not show up in the EMC.

Part 1 of this post will show how to manage these special mailboxes and Part 2 will cover how we actually utilize them.  Yes…these mailboxes are actually useful besides just keeping you from deleting that first mailbox database.  These mailboxes are called “arbitration” mailboxes and are used for managing approval workflow which we will go into further in Part 2.

So what error do we get when trying to delete this “empty” database? (your actual mailbox name will be different from the one I am using)
Again, according to the EMC there are no mailboxes in this database.  Let’s go to the shell and run the following command to see what mailboxes are really there.

Get-Mailbox –database “MB1” –Arbitration
So we have some GUID looking System mailboxes to deal with.  These are the arbitration mailboxes that need to get moved before we can delete the database.  When you prepped the domain during the installation of Exchange 2010, new AD objects were created and are linked to these mailboxes.  You can view these from AD Users and Computers in the Users container.
These match the ones from the EMS command output.  So let’s get these moved over to another production database so that we can delete the original database.  We can do this by running the following command.

Get-Mailbox –database “MB1” –Arbitration | New-MoveRequest –TargetDatabase “MB2”
Once the mailboxes are moved, the move requests will have to be cleared before the database can be deleted.  By navigating to the Recipient Configuration –> Move Request node in EMC, we can clear the request.
Now we can finally remove the database successfully!!!
Part 2 covers what these mailboxes are and how we can utilize them.


  1. This comment has been removed by a blog administrator.

  2. Hi Tim ,
    Congratulations on your Century of Answers on TechNet in just one month.
    Keep it up man
    Shafaquat Ali

  3. You find the correct problem in Exchange 2010 which encounter when you start.Its arbitration mailbox and moderated email.This problem is very well explained in this post and you can find the solution too.All the steps to do this are present in this post.take a look.

  4. Thanks for the info. In Exchange 2010 SP1, Administrator Audit Logging also uses an arbitration mailbox. It's not well documented and I had to contact MS support to get some info about that. See my post at

  5. This is a very informative post. I like the presentation of your post. Your present this post in a nice manner