A Support Customer of ours recently had an issue when trying to copy certain user accounts, every time they tried to do it they got the following error “Windows cannot create the object “Username” because: The name reference is invalid.”
We found out this issue was due to the users that they were trying to copy had the following Ad attribute “ShowinAddresssBook” set to a Deleted objects container (“CN=Default Global Address ListADEL:ebd91a78-78f0-4e1c-a5f2-cd321d9f3621,CN=Deleted Objects,CN=Configuration,DC=Test,DC=com“.)
We believe this occurred due to a recent Exchange 2003 decommission. To resolve this we ran the following command from Exchange 2010 management shell:
Get-mailbox | Where {$_.AddressListMembership –like “*deleted*” | Update-Recipient
This command updated the showinaddressbook attribute to a Exchange 2010 GAL and we were then able to copy the user accounts with no issues 
