Microsoft KB Archive/908625

= Outlook message data is sent over the network unexpectedly =

Article ID: 908625

Article Last Modified on 3/20/2006

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APPLIES TO


 * Microsoft Office Outlook 2003
 * Microsoft Outlook 2000 Standard Edition
 * Microsoft Outlook 2002 Standard Edition

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SYMPTOMS
When you work with e-mail messages in Microsoft Outlook, attachment or e-mail message data may be sent over the network unexpectedly. In this situation, you experience the following symptoms:
 * Performance may be reduced when the data for very large attachments is sent over the network.
 * The e-mail message or attachment data that is sent over the network is not encrypted if RPC encryption is not enabled for the e-mail profile.



CAUSE
This behavior occurs because the Microsoft Exchange Server store provider (Emsmdb32.dll) that is used for communication between Outlook and the Exchange store purposefully sends data to and from the server for various reasons. The Exchange store provider may perform in this manner to increase performance or to enable features in Outlook. All the scenarios in which data is sent over the network may not be expected or considered necessary by a user. However this behavior is necessary for the Exchange store provider. This behavior is part of the current design for MAPI clients and the store provider. Therefore, this should be considered an expected behavior.



MORE INFORMATION
Exchange client extensions that interact with Outlook e-mail messages may be specifically exposed to this design. When these client extensions intercept and handle events such as Onread and Onwrite to work with the data, the extension may not expect data to be sent over the network. However, data is sent over the network by design. Because this is part of the fundamental design of MAPI clients and the store provider, there is no easy way to prevent the data from being sent over the network.

Note By default, data that is sent over the network is encoded. However, the data that is described in this article not encrypted. You must enable RPC encryption for the Outlook profile if security is a concern in your organization.



STATUS
This behavior is by design.

Keywords: kbinfo kbtshoot kbnofix kbnetwork kbprb KB908625

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