You cannot enable the Exchange Server 2007 mailbox of a copied user account when the server on which the template user account was located does not exist

When you copy a mail-enabled user account in a Microsoft Exchange Server 2007 environment, the value of the msExchHomeServerName attribute of the user account is copied. If the server on which this user account was located no longer exists, and then you try to enable the mailbox of the copied user by using the Enable-MailUser command, you receive the following error message:

If the "Attribute is copied when duplicating a user" check box is selected in the Active Directory schema, the msExchHomeServerName attribute on the user account is preserved during the copy operation. However, when Exchange Server 2007 finds that this attribute is already populated with the value of a server name that no longer exist, the problem that is described in the �Symptoms� section occurs.

To resolve this problem, follow these steps:

1. Click Start, click run, and then type regsvr32 schmmgmt.dll to make the Active Directory Schema console available.
2. Click Start, click run, and then type mmc.exe to start Microsoft Management Console.
3. On the Console menu, click Add/Remove Snap-in, click Add, and then click Active Directory Schema. Click Add, click Close, and then click OK.
4. Navigate to Attributes, and then find the msExchHomeServerName attribute.
5. Right-click the msExchHomeServerName attribute, click Properties, and then click to clear the "Attribute is copied when duplicating a user" check box.

Now, the msExchHomeServerName attribute is not copied. Therefore, Exchange Server 2007 will successfully to enable the mailboxes of the copied users.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.