Article ID: 2902938 - View products that this article applies to.
You cannot preview Microsoft Office documents that are attached in shared folders by using Microsoft Outlook Web App in a Microsoft Exchange Server 2013 environment.
This issue occurs because shared mailboxes use the SecurityIdentifier value to identify the logged-on user’s address. However, Exchange returns the mailbox address instead of the logged-on user’s address to the value when you view the documents by using Outlook Web App.
To resolve this issue, install the following cumulative update:
(http://support.microsoft.com/kb/2892464/ )Description of Cumulative Update 3 for Exchange Server 2013
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.