The following table shows how Office Outlook 2007 features are supported by different versions of Exchange Server.

Note:
For Exchange Server 2003 and earlier versions of Exchange, the server can be found automatically only if the client machine is joined to a domain and the Exchange server topology is installed within the same Active Directory organization as the user object.

Using Office Outlook 2007 with an Exchange Server 2003 or later messaging server has a number of advantages. For example, the following Outlook features, which were introduced in Microsoft Outlook 2003 and are also available in Office Outlook 2007, work only with Exchange Server 2003 or later.

• Cached Exchange Mode using Download Headers   Cached Exchange Mode automatically downloads only headers when the user's operating system perceives that the user's connection mode is slow.

• Cached Exchange Mode using Download Headers and then Full Items   With this option, all item headers are downloaded first, followed by item bodies and other detailed information. Users can click item headers to immediately see specific items (headers, item bodies, and attachments).

• Outlook Anywhere (RPC over HTTP) connection support   You can configure user accounts to connect to an Exchange server over the Internet. This feature enables users to use the Office Outlook 2007 client for security-enhanced access to their Exchange Server accounts when they are traveling or are working outside their organization's firewall.

• Kerberos authentication   Outlook can use Kerberos authentication with Exchange Server 2003. The Kerberos network security protocol uses cryptography to help provide mutual authentication for a network connection between a client and a server, or between two servers.

• Performance tracking support    Office Outlook 2007 provides information about client processing that Exchange can use to help locate networking or server issues. For more information, see Exchange Server 2003 documentation.

Exchange Server 2003 and later versions of Exchange Server provide support for certain Outlook features, and Office Outlook 2007 works better with Exchange Server 2003 or later in several ways for other features. Several of these features were introduced in Outlook 2003—most notably for synchronization processing, user synchronization status reports, and junk e-mail filtering. Instant Search and automatic Exchange server discoverability are new in Office Outlook 2007.

Synchronization processing between Outlook and Exchange is enhanced in a number of ways, starting in Outlook 2003. For example, data exchanged between the Outlook client and Exchange Server 2003 servers is compressed, and the data buffer size is larger. In addition, the buffers are packed, so more compressed data is included in each buffer. With these features, more data can be transferred with fewer server calls. This is especially beneficial when users are synchronizing across networks that charge by the byte of data that is transmitted. When large information sets are downloaded—for example, when users update their mailboxes after they have been on vacation—cost can be significantly lowered and the transaction can be shortened with these improvements.

Another feature that users will notice is better status information about Cached Exchange Mode synchronization. With Exchange Server 2003 or later, the Outlook status bar shows detailed information about synchronization, such as:

• How many bytes have not been downloaded for the current folder

• How many items have not been downloaded in the current folder

• Approximately how long it will be until the current folder is synchronized

• Folder status, such as Up to Date and Last updated at date and time.

When it is used with Exchange Server 2003 or later, the Headers Only mode in Outlook provides a 256-byte plain text preview that includes part of the message body, rather than showing just the message header information. This message preview can help remote users to make better decisions about whether to download a whole message—which, for example, might include a large attachment.

Using Outlook with Exchange Server 2003 or later also helps to provide a better experience for users in filtering junk e-mail messages. The Junk E-mail Filter in Outlook provides some support for Outlook users with Cached Exchange Mode on versions of Exchange Server earlier than Exchange Server 2003. The experience is much improved with Exchange Server 2003 or later. To learn more about how Outlook junk e-mail filtering is supported with different versions of Exchange Server, see Configure junk e-mail settings in Outlook 2007.

Several features that are new in Office Outlook 2007 also work better with Exchange 2007. Instant Search works better with Exchange 2007 when you use Outlook in Online mode with a mailbox server, because Outlook can use the index on Exchange Server 2007 for searching. To enable Instant Search when you use Outlook with earlier versions of Exchange, you must configure Outlook to index user mailboxes for each Exchange client. This extra step is required because indexing in Outlook on the user's computer cannot be fully optimized, unlike the server indexing service that is implemented for Exchange Server 2007.

If users are configured to use Cached Exchange Mode, Office Outlook 2007 indexes the search locally, regardless of the Exchange server version. In addition, Office Outlook 2007 automatically detects the user's Exchange server with Exchange Server 2007. Automatic detection is also enabled under the following circumstances for earlier versions of Exchange: when the user's computer is joined to a domain and when Exchange is in the same domain as the user account.

Note:
You can configure Microsoft Exchange Server settings for Outlook profiles as part of your Office Outlook 2007 deployment. For more information about using the Office Customization Tool to customize Outlook profiles, see Specify Exchange settings in Office Customization Tool in the 2007 Office system.

Additional information regarding how Outlook and Exchange versions work together is listed below.

• Office Outlook 2007 includes the ability to automatically configure user accounts. To learn how the discovery mechanisms work and how to modify an XML file to configure AutoDiscover for your organization, download the Outlook Automatic Account Configuration whitepaper.

• For a description of how Office Outlook 2007 and Exchange 2007 features work together to provide a better experience for users, see Better together: do more with Microsoft Office Outlook 2007 and Exchange Server 2007.

• For a chart comparing features in Exchange Server 2007, Exchange Server 2003, and Exchange Server 2000, see Exchange Server Version Comparison.

• To learn more about Offline Address Book (OAB) Version 4, see OAB Version 4 in Exchange Server 2003 Service Pack 2.

This topic is included in the following downloadable book for easier reading and printing:

• Messaging guide for the 2007 Office release

• Planning and architecture for the 2007 Office release

See the full list of available books at Office Resource Kit information.