New Outlook for Web: Now known as "Outlook on the Web," the updated online service has new tools and capabilities including Sweep, Pin, Undo, single-line inbox view, inline reply, the ability to paste inline images, an option to suggest new meeting times, better HTML rendering, and new themes.

eDiscovery: A new, asynchronous architecture spreads the work across multiple servers, making eDiscovery faster and more scalable. The tool lets you search, hold, and export content located in public folders.

Better collaboration: Document sharing is easier in both Outlook 2016 and Outlook on the Web, which now let you attach documents as links from SharePoint 2016 and OneDrive for Business. This feature also enables coauthoring and version control.

Search: Searching your Outlook 2016 inbox is faster with Exchange 2016 on the backend. An intelligent search tool provides search suggestions, search refiners, people suggestions, and the option to search events scheduled on your calendar.

Simplified architecture: The architecture of Exchange 2016 resembles the deployment of Exchange in Office 365. Mailbox and client access server roles are combined, which simplifies the process of planning hybrid and on-premises deployments.

Greater extensibility: Outlook 2016 and Outlook on the Web have an expanded add-in structure so developers can build features directly into Outlook. Add-ins are integrated with the UI. They can appear as a button on the Outlook ribbon, as highlighted text in a message, or in the right-hand task window when writing a note.

High availability: Improvements to automated repair, like database divergence detection, make it easier to run Exchange Server 2016 in a highly available way. The new Exchange also includes stability and performance enhancements from Office 365.