Microsoft Exchange Server

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Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft. It is a part of their Windows Server System line of server products. The use of Microsoft Exchange is very widespread in large corporations using Microsoft infrastructure solutions. Among other things, Microsoft Exchange manages electronic mail, shared calendars and tasks, provides full support for mobile and web-based access to information, and can support very large amounts of data storage. It is positioned as a rival to the Lotus Notes / Domino server from IBM and competes with a number of competitors such as Scalix, Open-Xchange and exchange4linux.

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History

The original version of Exchange was envisioned as a x.400-based mail server that also supported the x.500 directory standard. This product replaced the Microsoft Mail product originally acquired from Network Courier. Exchange was a client server based mail system that used a single database store. The Exchange 4.0 Directory formed the initial foundation for Microsoft's Active Directory service, an LDAP-compliant directory server. Active Directory was later integrated into Windows 2000 as the foundation of Windows Server domains.

Exchange 5.5 was sold in two editions, Standard ("5.5/S") and Enterprise ("5.5/E"). They differ in database store size, "connectors," and clustering capabilities. The Standard edition has a database size limitation of 16GB, the Enterprise edition has a limit of 16TB - effectively unlimited for all practical purposes. The Standard edition is packaged with a Site Connector, MS Mail Connector, cc: Mail Connector, MS Notes Connector, Internet Mail Service, and Internet News Connector. The Enterprise edition adds on top of that: PROFS, X.400, and SNADS Connectors. The Enterprise edition can be clustered, while Standard cannot.

Exchange 2000 overcame many of the limitations of its predecessors, Exchange 4.0 and 5.5. 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. This, in turn, 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.

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Version history

  • 1996 - Exchange Server 4.0
  • 1997 - Exchange Server 5.0
  • 1997 - Exchange Server 5.5 (Standard Edition, Enterprise Edition)
  • 2000 - Exchange 2000 Server
  • 2003 - Exchange Server 2003 (Standard Edition, Enterprise Edition)
  • 2006 - Exchange Server"12" (in development)[1]
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Current version

The current version of Exchange is 2003 SP2. It can be run on Windows 2000 Server (only if Service Pack 4 is first installed) and 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. 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 sender-IP, reverse DNS ("Sender ID" framework), and RBL filtering which were standard on other open source and *nix-based mail servers (more info in "Exchange 2003 Anti-Spam Filtering" section, below), also new is the ability to drop inbound e-mail before being processed. There are also improved message and mailbox management tools, which allow administrators to execute common chores more quickly. Others, such as Exchange Conferencing Server have been extracted completely in order to form separate products. Microsoft now appears to be positioning a combination of Microsoft Office, Live Meeting and Sharepoint as its collaboration software of choice. Exchange is now to be simply email and calendaring.

Exchange 2003 is available in two 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 registry change is necessary to enable larger database sizes. Enterprise Edition allows a 16 TB maximum database size, and supports up to 20 databases per server.

Exchange 2003 is included with the Microsoft Small Business Server Product.

Microsoft Exchange Server uses a proprietary RPC protocol, of which only the API is documented (see MAPI), and is used by the Microsoft Outlook client. Email hosted on an Exchange server can be accessed by numerous client software packages including Lotus Notes. If configured, Exchange accounts can also be accessed through a web browser, known as Outlook Web Access (OWA).

Coupled with Windows Mobile 5.0 and SP2, Exchange Server 2003 supports "pushing" email to mobile devices - similar to the operation of BlackBerry devices: More info, http://www.microsoft.com/technet/prodtechnol/exchange/2003/sp2mobility.mspx and http://www.palmblvd.com/articles/2005/10/2005-10-19-Microsoft-Looks-to.html

Unlike Exchange Server 2000, Exchange Server 2003 no longer natively supports instant messaging for internal corporate systems. Microsoft released Live Communication Server 2005 to provide those services.

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


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Clustering

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, Active/Active mode may well be removed from the next release of Exchange altogether.

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.

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Future

For some time after the release of Exchange 2003, Microsoft's future plans for the product were unclear, with no new version promised. Edge Services, an add-on for the main product, was to have been been released sometime in 2005 but was dropped.

Finally, a January 2005 announcement from Microsoft filled in some gaps. The new version, currently called Exchange 12, or E12, is to be released on DVD only in 2006/07. The new version is to include voice mail integration, better search and support for Web services. The company also announced that the new version would run on 64-bit version of Windows only, pointing out the substantial performance benefits that 64-bit brings to the product. However, companies currently running Exchange on 32-bit hardware will be forced to replace it 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 OS simultaneosly with the E12 upgrade. This is because Exchange 2003 cannot be installed on Windows 2003 64-bit.

The first beta of E12 was released in December 2005 to a very limited number of beta testers; a wider beta available via TechNet Plus and MSDN subscriptions was released in early March 2006 according to the MS Exchange team blog, "You had me at EHLO.". More details about Exchange 12 can be found at the Exchange Preview Website

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Licensing

Like Windows Server products, Exchange requires Client Access Licenses, which are different than Windows CALs. However, you do not need Windows Server CALs for users only accessing the Exchange server software on each Exchange server. Most corporate license agreements include Exchange CALs.

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See also

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References

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External links

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