When you install Microsoft Exchange Server 2013 or upgrade to a cumulative update prior to Cumulative Update 13, SSLv3 is always enabled when setup has completed. After you install Cumulative Update 13, SSLv3 is always disabled when the setup is complete.
This issue occurs because SSLv3 was previously always enabled by the Exchange Server Setup process. To improve product security, it will be a known behavior change starting from Cumulative Update 13 for Exchange Server 2013 to always disable SSLv3.
This is the expected product behavior.
Microsoft has confirmed this change in behavior in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology that Microsoft uses to describe software updates.