Over the past ten years, Microsoft has released five major versions of Exchange Server: Exchange Server 4.0, Exchange Server 5.0, Exchange Server 5.5, Exchange 2000 Server, and Exchange Server 2003. Each release has strengths and weaknesses, and with each release we've enjoyed some major new functionality. Unfortunately, we've also often had to tweak the software or change the way we work or the way our network infrastructure is set up to accommodate a new release. Although Exchange Server 2007, formerly known as Exchange 12, isn't a departure in that regard, it incorporates functionality that administrators and users will be excited about. Let's look at some of the major new features in Exchange 2007, and I'll discuss the likely changes that administrators face with this version of Exchange.

Exchange 2007 Design Goals
Microsoft begins planning for an Exchange release well in advance—planning for Exchange 2007 began before Exchange Server 2003 even shipped. The point behind this advance-planning process is to let Exchange designers and developers identify trends in the computing world and figure out the best way to meet them; the hoped-for result is that the final product is relevant by the time it ships. This process has worked pretty well for Microsoft in the past. For Exchange 2007, Microsoft isolated three primary goals.

More control for IT administrators. Administrators have long complained about some aspects of Exchange 2000 and 2003, including the relative difficulty of helping nontechnical end users set up their Outlook profile and the complexity (some would say "richness") of the Exchange System Manager (ESM) tool. In addition, several different programming interfaces exist for writing scripts and tools that manipulate Exchange data, yet there are still some things you can do only through the ESM interface.

More Inbox value for end users. This phrase seems meaningless until you consider what "Inbox value" users actually get from their message, calendar, and contact data. Microsoft's vision for Exchange 2007 is to make all the data from the Inbox ubiquitously available from the desktop (through Outlook), the Web (through a revamped version of Outlook Web Access—OWA), mobile and wireless devices, and even telephones. There are also major improvements in the way Exchange 2007 handles meeting and resource booking—features that users will immediately welcome no matter what client they're using.

Active messaging protection. This is a fancy way of saying that Exchange 2007 is intended to do a better job of blocking viruses, filtering spam, and protecting mail content from tampering or interception along the delivery route.

These three categories are broad. Let's break down Exchange 2007's major new features according to feature area.

Architecture and Roles
Both Exchange 2000 and Exchange 2003 maintain two server roles: front-end servers handle client connections, and back-end servers contain mailboxes. In Exchange 2007, the concept of role separation has been extended to cover five server roles. One server can handle multiple roles simultaneously, and you can dynamically add or remove roles on an existing server without reinstalling Exchange. The five roles are:

  • Client Access Server (CAS). Proxies client connections, much like an Exchange 2003 front-end server would do. The CAS also provides OWA service.
  • Mailbox server. Holds mailboxes by default but can accept MAPI connections. You can combine the mailbox and CAS roles.
  • Edge Transport server. Performs message hygiene and filtering tasks. Edge Transport servers don't have to be part of an Active Directory (AD) forest and can safely be placed inside the network demilitarized zone (DMZ).
  • Hub Transport server. Routes mail between mailbox servers inside the organization.
  • Unified Messaging server. Routes communications between PBX or telephone systems, CASs, and mailbox servers.

If you want an Exchange 2003?style organization, you can use mailbox servers in place of your back-end servers, and CASs in place of the front-end servers. To better match your environment, you can design an architecture that separates the new roles by placing each on its own machine.

64-Bit Support and Scalability
In November 2005, Microsoft dropped a bomb with its announcement that Exchange 2007 would run only on 64-bit (i.e., x64) hardware. The announcement immediately generated discussion in various online communities, most of which centered on whether the change was a good move for Microsoft or not. A careful analysis shows that the 64-bit restriction is a sensible move on Microsoft's part. The vast majority of servers sold today are already 64-bit-capable; both AMD and Intel have been shipping server CPUs that support 64-bit address spaces for more than 18 months, and because these components cost the same as 32-bit components, they have been quickly adopted by major server manufacturers. This means that if you possess hardware purchased since January 2005, the odds are excellent that it's already 64-bit. If you're still on 32-bit hardware, you can align your hardware refresh cycle with your Exchange 2007 deployment; alternatively, you can buy new hardware when it's convenient and deploy Exchange 2007 on this hardware when the software ships.

Why did Microsoft make this decision? For several reasons, the most important of which involve scalability and performance. The two bottlenecks that limit the number of users you can host on an Exchange machine are typically the disk subsystem (on which you need lots of I/O operations per second—IOPS—to provide good performance for large numbers of users) and the amount of address space reserved for use by the kernel. Moving to a 64-bit addressing model means that you can put a huge amount of RAM into a server that Exchange can productively use to cache database pages. With large RAM installations, the number of disk requests Exchange has to make drops by as much as 70 percent, eliminating the storage system as a bottleneck. A bonus is that adding large amounts of RAM is typically cheaper than adding multiple physical disks. In addition, 64-bit addressing fixes the kernel resource problem by greatly increasing the address space available to the kernel.

ESM and Monad
The current ESM tool can be daunting to newcomers—its tree structure can be confusing even to experienced administrators. Learning which items in the tree control which settings or behaviors can take time. To make things simpler for administrators, Microsoft has dramatically revamped the appearance of the ESM console, as Figure 1 shows, moving to a three-pane design that looks like a less-cluttered ISA Server console. ESM is built totally on the Exchange Management Shell, which is an extended version of the Windows PowerShell ( formerly code-named Monad). This move is pure genius because it means that you can write scripts to do anything and everything that can be done in ESM. If you don't like the way some part of ESM works, you can write your own code to do things the way you want them done. (Microsoft hasn't announced any plans to let third-party code run within ESM's interface.) The Windows PowerShell is an extremely powerful and flexible scripting environment that you can extend by writing your own cmdlets (i.e., managed code objects) in C#, C++, or Visual Basic, and it ships with a broad set of cmdlets that you can use to configure Exchange directly.

In a move certain to generate discussion, Microsoft has decided to remove the Exchange-specific tabs that Exchange 2000 and Exchange 2003 add to the Microsoft Management Console (MMC) Active Directory Users and Computers snap-in. So, in Exchange 2007, account-management tasks such as creating mailboxes or setting user mailbox limits will require use of the ESM tool (or a script); creating a new user with a mailbox will require both the Active Directory Users and Computers snap-in and ESM.

Continuous Data Protection
Exchange 2007 breaks new ground by offering two new continuous-backup capabilities. Local continuous replication (LCR) makes a local copy of the Exchange database and log files on one server. Unlike disk mirroring, however, LCR makes a copy of the data by using Exchange APIs, so corrupted data isn't replicated like it would be on a mirrored disk. Clustered continuous replication (CCR) applies the same basic technology but lets you replicate data to another node in an Exchange cluster. CCR is big news because it essentially eliminates the requirement for a shared storage subsystem for your Exchange cluster—if you have enough bandwidth between nodes, you can easily build geographically distributed clusters. Accordingly, CCR will be huge for organizations wanting more disaster recovery flexibility, and LCR is a nice extension of "mini-high-availability" functionality to individual servers.

Web Services
One of the little-heralded new features of Exchange 2007 should be getting a lot more press: Exchange 2007 fully supports Web services. If you're not a developer, this news might not sound exciting—until you realize that Web services support unlocks all of the data in your Exchange store and all of the services Exchange offers by making them available to any Web services client. For example, I could easily write a Web services program on a Linux or Mac OS X workstation to access and manipulate data in an Exchange store or to request services (such as sending mail or playing a voicemail message) from a Windows Mobile device. Rather than the confusing mix of various APIs we need for Exchange 2000 and Exchange 2003, the Web services support in Exchange 2007 offers a unified set of interfaces that should make developing Exchange-based applications significantly easier.

Unified Messaging
One of the most exciting new features in Exchange 2007 is support for unified messaging (UM). Third-party vendors (notably, Cisco Systems and Adomo) have offered products that tie voicemail systems to Exchange—Exchange 2007's UM features do that and much more. For example, you can use a telephone to call your Exchange server, log in, and ask it (via touch-tone or voice) to tell you about your next appointment, and you can access your voicemail directly from your Inbox.

I'm a huge fan of the telephone-computer integration that Microsoft Live Communications Server 2005 and Microsoft Office Communicator 2005 offer; Exchange 2007 extends this integration so that Exchange acts as both a portal to and a storage mechanism for all types of communications. For example, the Unified Messaging server role provides a voice activated auto-attendant for incoming calls; provides Outlook Voice Access (OVA), a new telephone-based access method that supports text-to-speech (for reading your mail and calendar data to you) and speech-to-text (for figuring out what you say); and accepts and delivers voice messages to your Inbox for access through OWA 2007, Outlook 2007, or Windows Mobile clients.

Microsoft still hasn't announced a final list of which UM hardware and telephone systems the Exchange 2007 release version will support. In the meantime, you can test the Unified Messaging server role functionality by using a Session Initiation Protocol (SIP) software phone that supports SIP over TCP.

Message Hygiene and Policy
Exchange 2007's spam filter will look familiar to anyone who's used Microsoft Exchange Intelligent Message Filter (IMF) in Exchange 2003. However, the filtering engine in Exchange 2007 is a good bit more flexible, and some exciting new capabilities exist. For example, when users modify their safe and blocked sender lists from Outlook 2007, their changes are passed to the Edge Transport servers for use in inbound-message filtering. Thus, the users' sender lists enhance inbound message filtering, rather than function solely to filter messages after they're delivered to the mailbox store. Exchange 2007 also implements a policy system that lets you filter inbound or outbound messages by content (including the presence, absence, or type of attachment), and the antivirus interface has been enhanced to allow third-party products to filter messages in transit, not just upon arrival at a mailbox.

Lots More to Talk About
Space limitations prevent me from telling you about every new feature in Exchange 2007 here. There's much more to discuss (such as integrated compliance features, automatic updating for the IMF, and Outlook 2007 integration) and, as with most major product releases, some of the features in Exchange 2007 that people will be most excited about are seemingly small. Let me mention two in particular.

  • In previous versions of Exchange, you were limited to no more than 32KB of rules on a single mailbox. This limitation is removed in Exchange 2007, which will be welcome news to the many power Outlook users who want to create more complex systems of rules but haven't yet been able to.
  • You can easily customize most of the system messages Exchange 2007 generates for things such as mailbox quota warning messages and nondelivery reports (NDRs). Given the number of requests for it I've seen since Exchange 4.0 shipped, this is quite possibly the most-requested Exchange feature ever.

Stay tuned for more coverage of Exchange 2007's new features and functionality.