Microsoft Exchange Server

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Microsoft Exchange Server
Developer: Microsoft
Latest release: 2007 / 7 December 2006
OS: Microsoft Windows
Use: collaborative software
License: Proprietary
Website: http://www.microsoft.com/exchange

Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft. It is part of the Windows Server System line of server products and is widely used by enterprises using Microsoft infrastructure solutions. Exchange's major features consist of electronic mail, shared calendars and tasks, and support for the mobile and web-based access to information, as well as supporting data storage.

Contents

[edit] History

Exchange Server 4.0, released on June 11, 1996, was the original version of Exchange. Positioned as an upgrade to Microsoft Mail 3.5, which Microsoft had originally acquired from Network Courier, Exchange Server was actually an entirely new X.400-based client-server mail system with a single database store that also supported X.500 directory services. The directory used by Exchange was eventually moved to Microsoft's Active Directory service, an LDAP-compliant directory server. Active Directory was integrated into Windows 2000 as the foundation of Windows Server domains.

On May 23, 1997, Exchange 5.0 was released, which introduced the new Exchange Administrator console, as well as opening up "integrated" access to SMTP-based networks for the first time. Unlike Microsoft Mail (which required a standalone SMTP relay), Exchange 5.0 could, with the help of an add-in called the Internet Mail Connector, communicate directly with servers using the new mail standard. Version 5.0 also introduced a new Web-based email interface Exchange Web Access, this was rebranded as Outlook Web Access in a later Service pack. Along with Exchange Server version 5.0, Microsoft released version 8.01 of Microsoft Outlook, version 5.0 of the Microsoft Exchange Client and version 7.5 of Microsoft Schedule+ to support the new features in the new version of Exchange Server.

Exchange 5.5, introduced November, 1997, was sold in two editions, Standard ("5.5/S") and Enterprise ("5.5/E"). They differ in database store size, mail transport connectors and clustering capabilities. The Standard edition had the same 16GB database size limitation as earlier versions of Exchange, while the Enterprise edition had an increased limit of 8TB (although Microsoft's best practices documentation recommends that the message store not exceed 100 GB). The Standard edition includes the Site Connector, MS Mail Connector, Internet Mail Service (previously "Internet Mail Connector"), and Internet News Service (previously "Internet News Connector"), as well as software to interoperate with cc:Mail, Lotus Notes and Novell GroupWise. The Enterprise edition adds an X.400 connector, and interoperability software with SNADS and PROFS. The Enterprise edition also introduced two node clustering capability. Exchange 5.5 introduced a number of other new features including a new version of Outlook Web Access with Calendar support, support for IMAP4 and LDAP v3 clients and the Deleted Item Recovery feature. Exchange 5.5 was the last version of Exchange to have separate directory, SMTP and NNTP services. There was no new version of Exchange Client and Schedule+ for version 5.5, instead version 8.03 of Microsoft Outlook was released to support the new features of Exchange Server 5.5.

Following Exchange 5.5 on November 29, 2000, Exchange 2000, or version 6.0, overcame many of the limitations of its predecessors. For example, it raised the maximum sizes of databases and increased the number of servers in a cluster from two to four. However, many customers were deterred from upgrading by the requirement for a full Microsoft Active Directory infrastructure to be in place, and the migration process involving user-to-mailbox mapping and a temporary translation process between the two directories. This upgrade process required upgrading a company's servers to Windows 2000. Some customers opted to stay on a combination of Exchange 5.5 and Windows NT, both of which are no longer supported by Microsoft.

[edit] Exchange Server 2003

Exchange Server 2003 debuted on September 28, 2003 Exchange 2003 (currently at Service Pack 2), or version 6.5, can be run on Windows 2000 Server (only if Service Pack 4 is first installed) and 32-bit Windows Server 2003, although some new features only work with the latter. Like Windows Server 2003, Exchange 2003 has many compatibility modes to allow users to slowly migrate to the new system. This is useful in large companies with distributed Exchange environments who cannot afford the downtime and expense that comes with a complete migration.

One of the new features in Exchange 2003 is enhanced disaster recovery, which allows administrators to bring the server online quicker. This is done by allowing the server to send and receive mail while the message stores are being recovered from backup. Some features previously available in the Microsoft Mobile Information Server 2001/2002 products have been added to the core Exchange product, like Outlook Mobile Access and server-side ActiveSync, while the Mobile Information Server product itself has been dropped. Better anti-virus and anti-spam protection have also been added, both by providing built-in APIs that facilitate filtering software and built-in support for the basic methods of originating IP address, SPF ("Sender ID"), and DNSBL filtering which were standard on other open source and *nix-based mail servers. Also new is the ability to drop inbound e-mail before being fully processed, thus preventing delays in the message routing system. There are also improved message and mailbox management tools, which allow administrators to execute common chores more quickly. Others, such as Instant Messaging and Exchange Conferencing Server have been extracted completely in order to form separate products. Microsoft now appears to be positioning a combination of Microsoft Office, Microsoft Office Live Communications Server, Live Meeting and Sharepoint as its collaboration software of choice. Exchange is now to be simply email and calendaring.

Exchange 2003 is available in three versions, Standard Edition and Enterprise Edition. Standard Edition supports one message database per server, and supports databases up to 16 GB in size. Beginning with the release of Service Pack 2, Standard Edition allows a maximum database size of 75 GB, but only supports 18 GB by default; a change is necessary to make the database size either larger or smaller than the new default 18GB size. Enterprise Edition allows a 16 TB maximum database size, and supports up to 4 storage groups with 5 databases per storage group for a total of 20 databases per server.[1].

Exchange 2003 is included with both Microsoft Small Business Server 2003 Standard and Premium editions and is 32-bit only, and will not install on the various 64-bit versions of Windows Server 2003.

Microsoft Exchange Server uses a proprietary RPC protocol, of which only the API is documented (see MAPI). It was designed to be used by the Microsoft Outlook client. Email hosted on an Exchange server can be accessed using POP3 and IMAP4, with clients such as Mozilla Thunderbird and Lotus Notes. Both Microsoft Outlook and Novell Evolution are clients capable of using the advanced features of Exchange Server; Microsoft Entourage for Mac also has most of the advanced features implemented in the latest version. Exchange accounts can also be accessed through a web browser, known as Outlook Web Access (OWA). Exchange 2003 also features a WAP version of OWA, called Outlook Mobile Access (OMA).

Coupled with Windows Mobile 5.0 AKU2 or higher, Exchange Server 2003 SP2 supports "pushing" email to mobile devices - similar to the operation of BlackBerry devices. [2], [3]

Unlike Exchange Server 2000, Exchange Server 2003 no longer ships instant messaging for internal corporate systems. Microsoft released Live Communication Server to provide those services as a standalone program.

Exchange 2003 Anti-Spam Filtering: Exchange 2003 added several basic filtering methods to Exchange. They are not sophisticated enough to eliminate spam, but they can protect against DoS and mailbox flooding attacks. Exchange 2000 supported the ability to block a sender's address, or e-mail domain by adding '*@domain.com', which is still supported in the 2003 server. Added filtering methods in Exchange 2003 are:

  • Connection filtering - messages are blocked from DNS RBL lists [4] or from manually specified IP address/range
  • Recipient filtering - messages blocked when sent to manually specified recipients on the server (for intranet-only addresses) or to any recipients not on the server (stopping spammers from guessing addresses)
  • Sender ID filtering - Sender ID, a form of SPF
  • Intelligent Message Filter - A free Microsoft add-on that uses heuristic message analysis to block messages or direct them to the "Junk E-Mail" folder in Microsoft Outlook clients. [5]

[edit] Exchange Server 2007

For some time after the release of Exchange 2003, Microsoft's future plans for the product were not known. Edge Services, an add-on for the main product, was to have been released sometime in 2005 but was dropped. The new version, Exchange 2007, released on DVD in late 2006 to business customers as part of Microsoft's rollout wave of new products. It includes voice mail integration, better search and support for Web services, better filtering options, and a new Outlook Web Access interface.

Exchange 2007 will run on 64-bit x64 version of Windows only, pointing out the substantial performance benefits that 64-bit computing brings to the product. This limitation applies to supported production environments only; a 32-bit trial version is available for download and testing. However, companies currently running Exchange on 32-bit hardware will be forced to replace or migrate hardware if they wish to upgrade to the new version. Even those companies that are currently running Exchange on 64-bit capable hardware will still need to upgrade their server operating system simultaneously with the Exchange 2007 upgrade.

The first beta of Exchange 2007 (then named "Exchange 12") was released in December 2005 to a very limited number of beta testers. A wider beta was made available via TechNet Plus and MSDN subscriptions in March 2006 according to the Microsoft Exchange team blog,

On April 25, 2006, Microsoft announced that the next version of Exchange would be called Exchange Server 2007. More details about Exchange Server 2007 can be found at the Exchange Preview Website. This site has information about this version of Exchange and outlines key improvements:

  • Protection: anti-spam, antivirus, compliance, clustering with data replication, improved security and encryption
  • Improved Information Worker Access: improved calendaring, unified messaging, improved mobility, improved web access
  • Improved IT Experience: 64-bit performance & scalability, command-line shell & simplified GUI, improved deployment, role separation, simplified routing
  • "Exchange Management Shell": a new command-line shell and scripting language for system administration (based on the Windows PowerShell scripting language -- formerly called "Monad" -- developed for Windows Vista). Shell users can perform every task that can be performed in the Exchange graphical user interface plus additional tasks, and can program often-used or complex tasks into "scripts" that can be saved, shared, and re-used.
  • "Unified Messaging" that lets users receive voice mail, e-mail, and faxes in their mailboxes, and lets them access their mailboxes from cell phones and other wireless devices. Voice commands can be given to control and listen to e-mail over the phone (and also send some basic messages, like "I'll be late")
  • Removed the database maximum size limit. Database size is now limited by hardware capability and the window for backups and maintenance.
  • Increased the maximum number of storage groups and mail databases per server, to 5 each for Standard Edition (from 1 each in Exchange 2003 Standard), and to 50 each for Enterprise Edition (from 4 groups and 20 databases in Exchange 2003 Enterprise).

[edit] Clustering and High Availability

Exchange Enterprise Edition supports clustering of up to 4 nodes when using Windows 2000 Server, and up to 8 nodes with Windows Server 2003. Exchange 2003 also introduced Active/Active clustering, but for two node clusters only. In this setup, both servers in the cluster are allowed to be active simultaneously. This is opposed to Exchange's more common Active/Passive mode in which the failover servers in any cluster node cannot be used at all while their corresponding home servers are active. They must wait, inactive, for the home servers in the node to fail. Subsequent performance issues with Active/Active mode have led Microsoft to recommend that it should no longer be used. In fact, support for Active/Active mode clustering has been discontinued with Exchange Server 2007.

Exchange's clustering (Active/Active or Active/Passive mode) has been criticised because of its requirement for servers in the cluster nodes to share the same physical data. The clustering in Exchange provides redundancy for Exchange as an application, but not for Exchange data. In this scenario, the data can be regarded as a single point of failure, despite Microsoft's description of this set up as a "Shared Nothing" model. This void has however been filed by ISV's and storage manufacturers, through "site resilience" solutions, such as geo-clustering and asynchronous data replication.[6]

Exchange Server 2007 introduces new cluster terminology and configurations that address the shortcomings of the previous "shared data model".[7]

Exchange Server 2007 now provides built-in support for asynchronous replication modeled on "Log Shipping" in a CCR (Cluster Continuous Replication) clusters, which are built on MSCS MNS (Microsoft Cluster Service - Majority Node Set) clusters which do not require shared storage. This type of cluster can be inexpensive and deployed in one, or "stretched" across two datacenters for protection against site wide failures such as natural disasters. The limitation of CCR clusters is ability to have only two nodes and the third node known as "voter node" of file share witness that prevents "split brain" scenarios, generally hosted as a file share on a Hub Transport Server. Second type of clusters is the traditional clustering that was available in previous versions, and is now being referred to as SCC (Single Copy Cluster). In Exchange 2007 deployment of both CCR and SCC clusters has been simplified and improved where the entire cluster install process takes place during Exchange Server install. LCR or Local Continuous Replication has been referred to as the "poor man's cluster". It is designed to allow for data replication to an alternate drive attached to the same system and is intended to provide protection against local storage failures. It does not protect against the case where the server itself fails.

In February, the Microsoft Exchange team announced they are wrapping up the beta release of SP1 for Exchange 2007. It was announced that SP1 will include an additional high avabilibity feature called SCR (Standby Continuous Replication). Unlike CCR which requires that both servers belong to a Windows cluster, typically residing in the same datacenter, SCR can replicate data to a non-clustered server, located in a separate datacenter.

[edit] Licensing

Like Windows Server products, Exchange requires Client Access Licenses, which are different from Windows CALs. Most corporate license agreements include Exchange CALs. For Service Providers looking to host Microsoft Exchange, there is a SPLA (Service Provider License Agreement) available whereby Microsoft receives a monthly service fee in the place of the traditional Client Access Licenses.

[edit] Exchange Hosting

Microsoft Exchange Server can also be purchased as a hosted service. This not only eliminates the upfront cost of purchasing hardware and software, but also saves on the cost of hiring Exchange system administrators. Hosted Exchange services take care of licensing, antivirus, spam filtering, backups, patches, upgrades and 24x7 support to end users. To find a Microsoft Exchange Hosting provider, consult Microsoft's approved list from their Hosted Exchange Server Partner Directory.

[edit] See also

[edit] References

[edit] External links

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