Download : Microsoft Exchange Server 2016 Preview
Now you can download Microsoft Exchange Server 2016 Preview here - you can install the bits and get hands-on experience with the newest member of the Exchange family.
> Initial product documentation available @ TechNet Exchange Server 2016 library
> For more detailed information you can refer: http://blogs.technet.com/b/exchange/archive/2015/07/22/announcing-exchange-server-2016-preview.aspx
Hope this helps.