Running Outlook in Online mode
· Running Outlook in Online Mode moves the IO burden from the client to the server and doesn't address the disconnected laptop scenario.
Network impact and ability to optimize the client
· Cached Exchange Mode provides intelligent use of bandwidth. This functionality is enabled by synchronizing only headers on slow connections (connections that are slower than 128 kilobits per second [Kbps]). This functionality works only when a network connection is present.
· After messages have been cached locally, typical user operations do not cause interactions that block the server. Quickflagging, marking a message as read, replying, and editing require a small amount of data to be pushed up to the server to keep the mailboxes synchronized. However, the pushing of data occurs in the background. This behavior causes much faster access to messages and to attachments, because you work from the local copy instead of the server copy.
Outlook 2003 Cached Exchange Mode offers you the following benefits:
· Reduced server load. After messages are cached locally, re-opening the same message does not require server transactions.
· Reduced network load. After messages have been pulled over the network one time, subsequent access to those messages does not cause additional network traffic. Because messages are also compressed, there is an additional reduction on network load.
· When you turn on Cached Exchange Mode in Outlook 2003, and when the connection from your computer that is running Outlook 2003 to the Exchange Server 2003 computer is not available, Outlook switches to the Trying to connect state or to the Disconnected state. If the connection is restored, Outlook switches to the Connected state or to the Connected (Headers) state. Any changes that you made while you were offline are synchronized automatically when a connection to a server is available. You can continue to work while changes are synchronized.
· Additionally, Cached Exchange Mode causes no loss of conventional functionality. New e-mail notifications, full Global Address List details, free/busy lookup, public folder access, and delegate support function as expected. However, this is true only when a network connection to an Exchange Server computer is present.
What is the Level of Security around cached mode and how it is encrypted
The .ost file is similar to a personal folders (.pst) file, but the .ost file is automatically encrypted with compressible encryption. The encryption key is stored in two places: in the mailbox on the Exchange computer and in a local Messaging Application Programming Interface (MAPI) profile that is configured on the client workstation. If the key is lost from both locations, the .ost file is unreadable. When a client connects in Online mode, the key in the profile is checked against the key in the information store database. If the keys differ, the client copy of the key is overwritten with the key from the information store, and a new .ost file is automatically generated on the client workstation. When you reset an information store database, a new offline key is generated in each new mailbox; therefore, the current .ost file becomes unreadable at the beginning of the first successful online connection. Any changes that are made before the synchronization of the current .ost file are not uploaded.
Written by Daniel Kenyon-Smith