New features introduced in Exchange Server 2013

• Offline support in OWA: Emails and actions are automatically synced the next time connectivity is restored. 
• Client connectivity: CAS role is the point of connectivity for all clients in Exchange 2013. 
• Public folders: In 2013, public folders are now part of mailbox databases and high availability is achieved using DAG. 
• Site Mailboxes: Brings Exchange emails and SharePoint documents together. 
• Outlook Web App: Offers three different UI layouts optimized for desktop, tablet, and mobile phone browsers. 
• Ability to customize: Outlook and OWA by integrating apps from the Office marketplace. (Yes, this is a reference to the Agaves add-ins that Microsoft and partners will be making available via the new Office Store.) The new "Napa" tools and/or HTML5 are Microsoft's preferred ways for developers to build these. 
• Exchange Administrative Center (EAC): Replacement of the Exchange Management Console by a Web-based Exchange Administrative Center (EAC). 
• Support for up to 8TB disks: And multiple databases per disk via Data Availability Group (DAG) management. 
• Built in basic anti-malware protection: Ability for administrators to configure and manage settings from inside EAC. (Note: this feature can be turned off, replaced or "paired with premium services such as Exchange Online Protection for layered protection."). 
• New Data Loss Prevention (DLP): Capabilities for identifying and protecting "sensitive data." DLP policies are based on regulatory standards, including PII and PCI. Also: new policy tips in Outlook 2013 can be set to inform users about potential policy violations. 
• In-Place eDiscovery: Can be run across Exchange, SharePoint, and Lync (now Skype for Business) from a single interface.
• Combine Roles: A reduction in the number of available roles to two: a Client Access Server and a Mailbox Server role.
• FAST Search: Now integrated into Exchange 2013 managed store to provide a more consistent (across Microsoft servers) indexing and searching experience.
• The inclusion "Managed Store": The name of the rewritten information store processes, which are now written in C#. 
• Replication: Public folders are now stored in mailbox databases and can take advantage of Database Availability Groups for replication and high availability. 
• Data loss prevention: Capabilities that can be integrated into Transport Rules.