About Cached Exchange Mode

This feature requires you to be using a Microsoft Exchange Server e-mail account in Cached Exchange Mode.

Cached Exchange Mode provides you with a better experience when you use a Microsoft Exchange Server e-mail account. A copy of your mailbox is stored on your computer. This copy provides quick access to your data and is frequently updated with the mail server.

If you work offline, whether by choice or due to a connection problem, your data is still available to you instantly wherever you are. If a connection from your computer to the computer running Exchange server isn't available, Outlook switches to Trying to connect or Disconnected. If the connection is restored, Microsoft Outlook automatically switches back to Connected or Connected (Headers). Any changes you make while a connection to the server isn't available are synchronized automatically when a connection is available. You can continue to work while changes are synchronized.

When data is optimized for an Exchange server connection type, the type of items that are synchronized with your server mailbox are different. For example, when you use a fast connection, Outlook copies the header, body, and attachments of an e-mail item from the e-mail server to your computer. When a slower connection is selected, only headers are automatically downloaded. The body and any associated attachments are downloaded only when requested by you, or as necessary for synchronization with personal digital assistants (PDAs), auto archiving, and some client-side rules. In a slower connection environment, the Offline Address Book is also not automatically updated. However, you do have the option of manually requesting the update.

Note Downloading headers only is a feature available when you connect to Exchange Server 2003.

Cached Exchange Mode takes advantage of the ability of Outlook to automatically determine the speed of your connection to the Exchange server, and it optimizes data transmissions for that speed. When the On Slow Connections Download Headers Only setting is selected, Outlook stops automatically downloading full items and also leaves attachments on the server.

For example, you may use a laptop computer at your office and connect via a network cable to your corporate local area network (LAN). You have access to headers and full items, including attachments. You have quick access to the computer running Exchange server. If you disconnect the laptop from the LAN, Outlook switches to Trying to connect status. You can continue to work uninterrupted with your data. If the connection remains unavailable, Outlook switches to Disconnected, periodically checking for server availability. If you have wireless access, Outlook could reestablish a connection to the server and switch back to Connected status. You aren't required to change any setting or restart Outlook.

Later that day, you use a modem for dial-up access to your Exchange server. Outlook recognizes your connection is slow and automatically optimizes for that connection by downloading only headers and not updating the Offline Address Book. Additional optimizations are also made to reduce the amount of data sent over the connection.

By offering different levels of optimization, Outlook can adapt to changing connection environments, such as disconnecting from a corporate LAN, going offline, and then reestablishing a connection to the server via a slower dial-up connection. As your Exchange server connection type changes— LAN, wireless, cellular, General Packet Radio Service (GPRS), and offline— transitions are seamless and never require you to change settings or restarting Outlook.

Note Downloading headers only is a feature available when you connect to Exchange Server 2003.

You always have the option to manually set the connection behavior. In some cases, you may want to control your connection behavior and the amount of data transmitted to and from the Exchange server. At the office, when connected to a high-speed local area network (LAN), Download Full Items is probably the best option. If you connect via a service that charges by the amount of data you send and receive, which is common with cellular and GPRS connections, select Download Headers. The amount of data sent over the connection is reduced and your connection time shortened. You can then request only the full items you need.

Note Downloading headers only is a feature available when you connect to Exchange Server 2003.