Exchange 2016 Technical Preview is available for public since July, 2015 for testing and evaluate the features. which i have posted here during that time.
AI have posted how to install Exchange 2016 Technical Preview on Server 2012 R2 in my past Article.
Exchange released Exchange Server 2016 RTM today and it can be downloaded from here. If you have Office 365 Enrolled and have mailbox hosted from Exchange Online, You could have been seen the Exchange 2016 features are already implemented and most of the features you already got it there.
Exchange 2016 builds on and improves features introduced in Exchange 2013, including Data Loss Prevention, Managed Availability, automatic recovery from storage failures, and the web-based Exchange admin center.
Significantly improved in the areas of Better Collaboration, Lightening-Faster Search, Outlook on the Web, simplified architecture(Removed CAS Role which available in Exchange 2013),and improvements on High Availability.
All other features of the Exchange 2016 has been listed in the Microsoft Article.
Stay Tuned for the next article on complete coverage of Exchange 2016 features and updates.