Exchange 2010 disconnect AD user from mailbox and reconnect the mailbox to a new copy of the same user with a different username

Question

How can i get the following done:
Exchange 2010 disconnect AD user from mailbox and reconnect the mailbox to a new copy of the same user with a different username?
i nmust do this for 16 users TODAY, SO PLEASE HELP ME OUT HERE.
Thanks in advance!!
kind regards,
Rene Veldman
System Administrator Teidem bv, The Netherlands.

Answer 1

Rene,
Why are you not changing the username of the existing account, instead of deleting the existing one and creating a new one?
If you truly need to delete and create new, you can save the GUID for the mailbox (Get-MailboxStatistics <mailbox alias> | Fl MailboxGuid), mail disable the existing account (Disable-Mailbox <mailbox alias>
will work), clean the mailbox database it was hosted on (Clean-MailboxDatabase
<database name>), then create your new account and recover the existing mailbox to that new account (Connect-Mailbox -Identity <Guid from before> -Database <Database name> -User <SAM account name of new account> -Alias
<what you wish to set the alias to>).  In PowerShell, for all steps, you would do the following:
$MbxAlias = <mailbox alias>
$NewMbxAcct = <SAM Account Name for new account>
$NewMbxAlias = <new alias for mailbox>
$DomCtrl = (dir env:\LOGONSERVER).Value.Substring(2)
$MbxGuid = (Get-MailboxStatistics $MbxAlias -DomainController $DomCtrl).MailboxGuid
$MbxDb = (Get-Mailbox $MbxAlias -DomainController $DomCtrl).Database
Disable-Mailbox $MbxAlias
Clean-MailboxDatabase $MbxDb
Connect-Mailbox -Identity $MbxGuid -Database $MbxDb -User $NewMbxAcct -Alias $NewMbxAlias -DomainController $DomCtrl
You will need to supply the information in bold in the above commands, and you will need to create the new account before you run the above commands.  I include direct use of a specific domain controller so you won't need to worry about replication. 
If you are changing the account from one domain to another, this will not help, and you will need to wait for replication throughout the process, running the commands individually.