Can't delete Exchange 2003 Mailbox DB after migration to Exchange 2010

I have almost completed the migration of Exchange 2003 to Exchange 2010.

I have been following this guide:

I have all the mailboxes running on Exch 2010. I have just Moved all Replicas from the Public Folder Database. I kept refreshing the Public Folder Instances until it was empty. I created the new Public Folder Container in the Exchange Administrative Group (FYDIBOHF23SPDLT) and dragged the Public Folders into it.
I was then able to delete the Public Folder store and then was able to Dismount Store. But now I can't delete the Mailbox Store. i get this message:

'One or more users currently use this mailbox store. these users must be moved to a different mailbox store or be mail disabled before deleting this store.
ID no: c1034a7F
Exchange System Manager'

But when I open Logons or Mailboxes in the Store, they are both empty.

Any ideas on how to get over this bump? Or do I even need to fix it? Or can I just proceed to Step 15: Uninstall Exchange 2003?

Who is Participating?
Simon Butler (Sembee)ConsultantCommented:
The fact that mailboxes is empty just means the users never used the mailbox. Often happens, particularly with service enabled account.
I have a process to find those mailboxes here:

Gareth GudgerCommented:
Hey Greg,

You'll need to find those users first. Chances an account or two is still claiming its home server is 2003.

You can find these by doing a Find in Active Directory Users and Computers

Right click on the domain, do a Find. In the Find dialog click Advanced. I think you search on Field >> User and not sure what after that. My current lab has never had 2003 in it. But I think the field may be Home Server from memory.
Gareth GudgerCommented:
Sweet. My memory wasn't far off. Thanks Simon!!
gregmiller4itAuthor Commented:
Ok, thanks guys, I have managed to identify two accounts. They are 'SystemMailbox{...lots of numbers...} and the renamed Domain Admin account (i.e. it was the original 'Administrator' account for the SBS 2003 box and I renamed it to be something trickier than 'Administrator').

There were no Exchange attributes for the SystemMailbox. I wasn't able to move the mailbox for the Admin account, but I was able to remove the mailbox. Once that was done I was able to successfully delete the Mailbox Store on the SBS 2003 box.

I was then able to find and remove the routing group connectors.
I was able to remove both of the Recipient Update Services.

At this point I am now ready to uninstall Exchange 2003. It does not appear in Add/Remove Programs as suggested by the guide. I suspect that this is because Exchange is part of SBS 2003. I will see what I can find to get rid of Exchange out of SBS 2003. Otherwise I will post another question.

Thanks heaps guys.
gregmiller4itAuthor Commented:
Update: I found that Exchange 2003 was an option in 'Small Business Server 2003' in Add/Remove Programs. So just had to 'change' SBS 2003 and remove Exchange and now it is gone!

Next step....migrate from Exchange 2010 to Exchange 2013.
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