Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows XP and Windows Vista
Consider the following scenario:
You configure Microsoft Office Outlook 2007 to run in Cached Exchange Mode. In this case, Outlook 2007 uses an offline folder (.ost) file to store e-mail messages and other items.
Outlook 2007 has access to one or more personal folders (.pst) files.
When you reply to a message that is stored in an offline folder, you manually copy the message to a personal folder.
You copy the reply to this message from the Sent Items folder in the offline folder to the Sent Items folder in the same personal folder.
In this scenario, when you log on to the online account that uses this personal folder, the Outbox folder indicates that a message is waiting to be sent. This message is displayed only in Outlook Web Access (OWA). The message is not displayed in Outlook 2007.
How to obtain the hotfix
This issue is fixed in the Outlook 2007 Hotfix Package that was released on February 7, 2008. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
948716 Description of the Outlook 2007 hotfix package: February 7, 2008
After you install the hotfix, you must also add registry data to your Outlook client to enable the fix.
Note If you configure the registry data to enable this fix, Outlook reverts to the earlier version behavior in which sent messages are uploaded two times to the server that is running Microsoft Exchange when you are running in cached mode. For detailed information, see the "More Information" section.
Fix it for me
To enable this hotfix automatically, click the Fix it button or link, click Run in the File Download dialog box, and then follow the steps in the Fix it wizard.
Note: Because this change is related to a hotfix, you must install the hotfix in addition to running the Fix this problem wizard. If you only run the Fix this problem wizard and you do not install the hotfix, the problem will not be resolved.
Note After you install this hotfix and add the registry data to enable the hotfix, messages that were displayed in Outbox before the installation of the hotfix continue to appear in OWA. This hotfix prevents the problem that is resolved by this hotfix only for new email messages. If you have to remove messages that continue appear in the Outbox folder, you must remove them by using OWA.
Let me fix it myself
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
To enable this hotfix, follow these steps:
Exit Outlook 2007.
Start Registry Editor.
In Windows Vista, click Start , type regeditin the Start Search box, and then press ENTER.
If you are prompted for an administrator password or for confirmation, type the password or click Continue.
In Windows XP, click Start, click Run, type regedit, and then click OK.
Locate and then right-click the following registry subkey:
On the Edit menu, point to New, and then click DWORD Value.
Type SendOne, and then press ENTER.
Right-click SendOne, and then click Modify.
In the Value data box, type 0, and then click OK.
On the File menu, click Exit to exit Registry Editor.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
In Outlook 2007 or in Microsoft Office Outlook 2003 together with a Microsoft Exchange Server 2003 mailbox, Outlook performs the following actions when you send a message in cached mode:
Outlook sends the message (this is the first upload to Exchange).
Outlook puts a copy of that message into your local (.ost) Sent Items folder.
Outlook synchronizes the Sent Items folder with Exchange (this is the second upload to Exchange).
However, in Outlook 2007 together with a Microsoft Exchange Server 2007 mailbox together with or a Microsoft Exchange Server 2010 mailbox, Outlook uses a different sending process, and the message is uploaded only one time to the Exchange server.
If you configure the registry data that is listed in this article (SendOne = 0), this new Outlook 2007 functionality is disabled. In this case, Outlook reverts to the earlier version behavior of uploading sent messages two times to Exchange.