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You cannot connect over the Internet to Exchange Server 2003 from Outlook 2007 or from Outlook 2003
Article ID: 831060 - View products that this article applies to.
When you try to use Microsoft Office Outlook 2007 or Microsoft Office Outlook 2003 to connect over the Internet to your mailbox on a Microsoft Exchange Server 2003 based-computer, you are prompted for your logon credentials many times, and you do not connect to Exchange Server 2003.
This behavior occurs if an outbound proxy authentication is required, and if you use Remote Procedure Call (RPC) over HTTP to connect to an Exchange Server 2003 account. When Outlook is using RPC over HTTP, the default timeout is 45 seconds. If RPC over HTTP takes longer than 45 seconds to connect, the connection is not successful.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/322756/ )How to back up and restore the registry in Windows
To resolve this behavior, you can add the ConnectTimeout, the ConnectTimeoutLow, and the RFRTimeoutDWORD values to the RPC registry key. To do this, follow these steps.
Note All the "connect timeout" registry values that are mentioned in the following steps are expressed in milliseconds (ms).
When Outlook tries to connect to each server type, Outlook uses the registry values that you added in the Resolution section to determine how long to wait before the connection is considered a failed connection (a time-out connection) and the connection is dropped.
Article ID: 831060 - Last Review: September 20, 2011 - Revision: 6.0