Exchange 2010 New-MoveRequest Fails

I just had an issues when I tried to Migrate some mailboxes from Exchange 2003 to 2010

We have 2 Internal Domains and SMTP namespace sharing setup between Exchange 2003 in old Domain and Exchange 2010 in the new Domain.

Users and been mirgated using ADMT. All users in the new Domain have been mail enabled (using a script). The Mailboxes have moved using New-MoveRequest from the Exchange Powershell.

Most mailboxes migrated without any problems but we had some fail with the error:

Cannot find a recipient that has mailbox GUID.

I found that some of the mail enabled accounts didn't have the targetAddress attribute set.

Setting the email adress on the targetAddress attribute fixed the problem...
BTW: There other reasons for getting this message such as the GUID being different.

After the Mailbox migrated this attribute returned to <not set> which is correct if the Mailbox is inside the local Exchange Organisation.