In this case, the tenant was in a hybrid scenario with Exchange 2010 on prem.  When he was attempting to move a few mailboxes back to on prem he was getting the following error:

Error: MigrationPermanentException: You shouldn't migrate mailbox ‎'John Doe‎' to Exchange 2010 or an earlier version while the user's Instant Messaging contact list is stored in Exchange. If you do, the user could permanently lose access to their Instant Messaging contact list, which will cause serious data loss. The Exchange copy might be the only copy of this user's contact list. To continue, please contact your Instant Messaging administrator and make sure that the user's contact list is moved back to the Instant Messaging server. After this has been done, you should be able to complete this migration. If you must migrate the mailbox despite the potential data loss, you can do so by running ‎'Set-UMMailbox mailboxID -ImListMigrationCompleted $false‎'.

The cause of receiving this message is that at some point, the user logged in using the Lync 2013 client.  Once this is done and the mailbox is on Exchange 2013, a feature called Unified Contacts Store is enabled.  This removes the user's Lync contacts from the Lync database and places them into Outlook.  In order for this to happen, three conditions have to be met. 

1) User must have a mailbox on an Exchange 2013 server

2) User must be on a Lync 2013 server

3) User must log in with the Lync 2013 client.

The real problem came when the administrator tried to run the Set-UMMailbox command referenced in the error, and got a new error stating the referenced mailbox was not UM enabled.  This could be resolved by changing the 0365 license assigned to the user, however in this case the tenant did not have any of the appropriate license available.  Fortunately, this situation has been repaired in a way.  The switches referenced in the error now work with the Set-Mailbox command, so the proper command would be:

Set-Mailbox mailboxID -IMListMigrationCompleted $false.

Hope this helps anyone that feels stuck with this error.

Group mailbox had an automated reply set.  It is important to note that while the reply was automated, it was created using the rules wizard, not the OOF wizard.

If e-mail is sent directly to the mailbox, the sender receives the reply.  If however an e-mail is sent to a distribution group the mailbox is a member of, the reply never shows up.  We have documented this scenario in 2007 and 2010 that the fix for this is to check the box for Allow Out Of Office replies to sender in the properties of the Distribution Group.  However, we do not expose this attribute in the GUI in 2013.  Instead the following powershell line needs to be run:

Set-DistributionGroup aliasofDG –SendOofMessageToOriginatorEnabled $True

 Once that is set, the rule fired properly and the reply is received by the sender.  The down side to this of course is if anyone else on the DG sets OOF, then the sender will also get their OOF message.