Symptoms
When you access your mailbox by using Outlook Web App in a Microsoft Exchange Server 2013 environment, the first email message is selected and marked as read automatically.
Cause
This issue occurs because of a by design feature in an Exchange Server 2013 environment.
Resolution
To resolve this issue, install Cumulative Update 9 for Exchange Server 2013.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
