Outlook 2007 prompts you repeatedly for a password under certain network conditions

Under certain network conditions, Microsoft Office Outlook 2007 prompts you repeatedly for a password. If you do not enter a password or if you enter an incorrect password, Outlook 2007 may silently enter Offline mode. In this case, you do not receive an error message or a notification, and you will not be connected to the mailbox.

Important Do not apply this hotfix if an account lockout policy has been applied.

For an overview of the account lockout policy, visit the following Microsoft TechNet Web site:

How to obtain the hotfix

This issue is fixed in the Outlook 2007 hotfix package 957909. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

How to enable the hotfix

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: To enable the hotfix, follow these steps:

1. Exit Outlook 2007.
2. Start Registry Editor.
   • In Windows Vista, click Start
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     , type regedit in the Start Search box, and then press ENTER.
     
     
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     If you are prompted for an administrator password or for confirmation, type the password or provide confirmation.
   • In Windows XP, click Start, click Run, type regedit in the Open box, and then click OK.
3. Locate and then click to select the following registry key:
   HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC
   Note If the RPC key does not exist, follow these steps:
   1. Right-click the Outlook key, point to New, and then click Key.
   2. Type RPC, and then press ENTER.
4. After you select the key that is specified in step 3, point to New on the Edit menu, and then click DWORD Value.
5. Type UseWindowsUserCredentials, and then press ENTER.
6. Right-click UseWindowsUserCredentials, and then click Modify.
7. In the Value data box, type the value that you want to use, and then click OK.
   
   Note When you set the UseWindowsUserCredentials value to 1, only the user's desktop credentials will be used. The following scenarios may help you determine the value that you want to use.
   • Account: Domain
     UseWindowsUserCredentials: 0 (or not present)
     Protocol: TCP, HTTP with NTML authorization
     Result: Connect to Microsoft Exchange without prompting for user credentials.
   • Account: Non Domain
     UseWindowsUserCredentials: 0 (or not present)
     Protocol: TCP, HTTP with NTLM authorization
     Result: Prompt for user credentials and connect to Microsoft Exchange.
   • Account: Domain
     UseWindowsUserCredentials: 1
     Protocol: TCP, HTTP with NTLM authorization
     Result: Connect to Microsoft Exchange without prompting for user credentials.
   • Account: Non Domain
     UseWindowsUserCredentials: 1
     Protocol: TCP, HTTP with NTLM authorization
     Result: Does not prompt for user credentials, and will not connect to Microsoft Exchange. Remains in the disconnected state, occasionally trying to connect.
   • Account: Domain
     UseWindowsUserCredentials: 1
     Protocol: HTTP with Basic authorization
     Result: Prompts for user credentials and successfully connects to Microsoft Exchange. Additionally, it will continue to prompt you if you mistype your password.
   • Account: Non Domain
     UseWindowsUserCredentials: 1
     Protocol: HTTP with Basic authorization
     Result: Prompts for user credentials and successfully connects to Microsoft Exchange. Additionally, if you mistype your password, it will continue to prompt you.
   • Account: Domain
     UseWindowsUserCredentials: 1
     Additional Steps: When you configure the profile, select Always prompt for username and password.
     Result: Prompts for user credentials and successfully connects to Microsoft Exchange.
8. On the File menu, click Exit to exit Registry Editor.

You can use the following registry entry to disable the credentials prompts when you receive an authentication error on credentials.

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC\DisableTransientFailureAuthPrompts (DWORD)

(default to FALSE, 1 is TRUE, and 0 is FALSE)

You can use the following registry entry to set a timeout period. If we do receive an authentication error, attempts to acquire another set of credentials will fail for a timeout period set in this registry entry.

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC\TransientFailureBackoff (DWORD)

(defaults to 10 sec, 10000 sec - 10 sec)

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

This hotfix will not resolve this problem if the following conditions are true:

• You have multiple Microsoft Exchange Server accounts that use different user credentials.
• You set the UseWindowsUserCredentials value to 1 in the registry.

For example, you log on to Windows as Fourthcoffee\User1. However, you start Outlook with a profile for the mailbox of Fourthcoffee\User2.

In this scenario, Outlook connects to Active Directory by first doing a referral remote procedure call (RPC) against the Exchange Server. This is followed by a second RPC to Active Directory that the referral provides. Neither of these RPCs requires any information about the mailbox account. In this case, the mailbox account is Fourthcoffee\User2.

By default, Outlook always tries the credentials that you use to log on to the computer first, in this case Fourthcoffee\User1. Therefore, this connection is considered successful. That is, the computer credentials for Fourthcoffee\User1. Then, Outlook tries to connect to the mailbox for Fourthcoffee\user2. Because the credentials for Fourthcoffee\User1 were successfully used during the Active Directory referral process, Outlook tries these same credentials to log on to the mailbox for Fourthcoffee\User2. Because Fourthcoffee\User1 does not have permissions to the mailbox for Fourthcoffee\User2, the mailbox logon fails. Access is denied. Because UseWindowsUserCredentials is set to 1 in this example, Outlook uses only the desktop credentials and suppresses the credentials prompt. Therefore, it silently fails repeatedly.