What's New In Exchange Server 2013

Microsoft recently released Exchange Server 2013, labeling it "the new Exchange." (This interesting branding decision implicitly labels all other versions of Exchange as "old," with all the negative connotations that label carries.) Understanding what's new in Exchange 2013 requires us to dig into the architectural and feature changes that Microsoft has made -- some (but not all) of which the company is touting heavily.

Architectural Changes

If you remember Exchange Server 2003, then the major architectural change in Exchange 2013 will seem very familiar. There are now only two roles: the Mailbox server role and the Client Access server role.

This setup is essentially the same as the front-end/back-end architecture in Exchange 2003, although there are major implementation differences. Microsoft decided to split the roles in this way to dramatically simplify implementation at large scales. Tight coupling between the server roles no longer exists: The Client Access server role doesn't keep any state or session data and can be upgraded (or rebooted) independently of the Mailbox server role, and vice versa. This change has several interesting implications:

• The Exchange 2013 Client Access server role (formerly called the Client Access Front End in Microsoft internal documents) becomes essentially a super-smart proxy that no longer needs to maintain state or affinity. Much of the complexity of configuring the Exchange 2010 Client Access server role vanishes.
• Load balancing is completely different. With no requirement for affinity, load balancers that work at Layer 4 (the network layer) of the OSI model can be used. (There are still cases in which it makes sense to use application-aware load balancers that apply greater intelligence to deciding when and how to distribute load between servers.)
• Remote Procedure Call (RPC) for mailbox access is dead. You can still use RPC over HTTP Secure (HTTPS), but the RPC Client Access service is no longer part of the equation. This change enables the use of HTTPS-based load balancing, without the Exchange 2010 requirement for separate namespaces or certificates.
• The Hub Transport server role is gone, its responsibilities split between the Client Access server and Mailbox server roles. Given that few Exchange 2010 sites had combined the Mailbox and Hub Transport roles, this change isn't huge.
• New services run on the Mailbox server, so you might need to re-examine the scaling and sizing decisions that you made for Exchange 2010 deployments.

Brand-New Features

As is typical for a new release of a major product, Exchange 2013 is full of new features. Knowing what to label "new" can sometimes be difficult because of Microsoft's habit of making major enhancements to existing features, but several genuinely fresh features are included. The most significant one is arguably the new managed availability functionality. Microsoft describes managed availability thusly on the Exchange Team Blog:

Managed availability is a monitoring and recovery infrastructure that is integrated with Exchange's high availability solution. Managed availability detects and recovers from problems as they occur and as they are discovered.

This description neatly captures the major points of managed availability: It focuses on detecting problems that the end user will notice and then repairing them automatically whenever possible. The Exchange 2013 managed availability implementation accomplishes this task by performing several kinds of automated checks that probe various parts of the infrastructure. Based on the results of these tests, a variety of automated responders can take action. These actions can range from restarting the responder service, to taking a protocol on a machine out of service (which allows client traffic to be sent to another machine running the same protocol), to forcing a server reboot and restart. There's also the escalate responder, whose job it is to fire an event that triggers special behavior in System Center Operations Manager or other monitoring software. In this way, Exchange has a customized method for indicating a high-priority failure that requires human intervention. Managed availability represents an ambitious effort by Microsoft to bring high-scale, datacenter-style management to Exchange. This effort offers a lot of potential, although I'm reserving judgment on its worth until I see it proven in the field.

Another major change is the availability of a single integrated e-discovery experience. You can now perform discovery searches that include Exchange mailboxes and public folders, archived Microsoft Lync conversations, and material that's stored in Microsoft SharePoint from a single SharePoint-based interface. Although this feature requires that you deploy SharePoint 2013, organizations that need to perform discovery searches will find this feature valuable because it enables self-service discovery searches for users with appropriate permissions.

Exchange 2013 also includes a group of features that are lumped under the rubric of data loss prevention (DLP). The goal of these features is to reduce the risk that your organization will commit or suffer breaches of sensitive data such as personally identifiable information (PII) of customers, data that must be protected under regulations such as the US Health Insurance Portability and Accountability Act (HIPAA) or European Union Data Protection Directive (EUDPD), or data that you just don't want to be disclosed. DLP features include a robust set of transport rule–like tools for scanning messages for sensitive data, a predefined set of policies for common regulatory requirements, and tools for customizing the included items or building your own.

It will be interesting to see which of these features drive Exchange 2013 adoption. Some are likely to be of interest to a small number of large customers, whereas a few others seem clearly targeted at a broader audience.