After you upgrade to Microsoft Exchange Server 2013 Cumulative Update 6, you cannot see online archive mailbox in Microsoft Outlook.
This issue occurs because autodiscover is returning the primary mailbox settings for the online archive mailbox.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 3003068 - Last Review: Dec 9, 2014 - Revision: 1
Exchange Server 2013 Enterprise, Exchange Server 2013 Standard Edition