Assume that you have a hybrid deployment of Microsoft Exchange Online in Microsoft Office 365 and of your on-premises Microsoft Exchange Server 2010 environment. When you off-board a mailbox from Office 365 to Exchange Server 2007, it finishes with the CompletedWithWarnings status. However, it is unfinished. Some post cleanup jobs are not performed.
Note This issue does not affect Exchange Server 2013 hybrid server or affect off-boarding a mailbox to an Exchange Server 2010 environment.
This issue occurs because the NotConnectedPermanentException exception is thrown when you try to verify the connection to the target mailbox.
To resolve this issue, install Update Rollup 8 for Exchange Server 2010 Service Pack 3.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
If you experience issues when you move mailboxes to Exchange Online in Office 365, you can run the Troubleshoot Office 365 Mailbox Migration tool. This diagnostic is an automated troubleshooting tool. If you're experiencing a known issue, you receive a message that states what went wrong. The message includes a link to an article that contains the solution. Currently, the tool is supported only in Internet Explorer.