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Winmail.dat sent as an email attachment in Outlook 2007 and 2010

Problem description

When you use Microsoft Office Outlook 2010 or Microsoft Office Outlook 2007 to send an email message, the recipient of the message sees an attachment that is called Winmail.dat. This article helps you fix the problem.

To have us fix this problem for you, go to the “Fix it for me” section. If you would rather fix this problem yourself, go to the “Let me fix it myself” section.
Resolution

Fix it for me

To fix this problem automatically, first install hotfix 957692 then click the Fix this problem link. Then click Run in the File Download dialog box, and follow the steps in this wizard.


Note This wizard may be in English only. However, the automatic fix also works for other language versions of Windows.

Note If you are not on the computer that has the problem, you can save the automatic fix to a flash drive or to a CD, and then you can run it on the computer that has the problem.

Now go to the "Did this fix the problem?" section.

Let me fix it myself

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:
322756 How to back up and restore the registry in Windows

To prohibit Outlook 2010 from sending the Winmail.dat file
Follow these steps:
  1. Add the DisableTNEF registry entry. To do this, follow these steps:
    1. Exit Outlook 2010.
    2. Start Registry Editor.
      • In Windows 7, click Start the Start button, type regedit in the Search programs and files box, and then press Enter.
      • In Windows Vista, click Startthe Start button, type regedit in the Start Search box, and then press Enter.

        User Account ControlIf 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, and then click OK.
    3. Locate and then select the following registry subkey:
      HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Preferences
    4. On the Edit menu, point to New, and then click DWORD Value.
    5. Type DisableTNEF, and then press Enter.
    6. Right-click DisableTNEF, and then click Modify.
    7. In the Value data box, type 1, and then click OK.
    8. Exit Registry Editor.
    9. Restart the computer.
To prohibit Outlook 2007 from sending the Winmail.dat file
Follow these steps:
  1. Install hotfix 957692.

    For more information, click the following article number to view the article in the Microsoft Knowledge Base:
    957692 Description of the Outlook 2007 hotfix package (Outlook.msp): October 28, 2008
  2. Add the DisableTNEF registry entry. To do this, follow these steps:
    1. Exit Outlook 2007.
    2. Start Registry Editor.
      • In Windows Vista, click Startthe Start button, type regedit in the Start Search box, and then press Enter.

        User Account ControlIf 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, and then click OK.
    3. Locate and then select the following registry subkeys:
      HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Preferences
    4. On the Edit menu, point to New, and then click DWORD Value.
    5. Type DisableTNEF, and then press Enter.
    6. Right-click DisableTNEF, and then click Modify.
    7. In the Value data box, type 1, and then click OK.
    8. Exit Registry Editor.
    9. Restart the computer.

Now go to the "Did this fix the problem?" section.
Did this fix the problem?
Check whether the problem is fixed. If the problem is fixed, you are finished with this article. If the problem is not fixed, you can contact support.
Cause
This problem occurs when the software that the recipient is using does not support certain message formats or certain features that are included in the email message.
More information
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
278061 Email received from a sender using Outlook includes a Winmail.dat attachment
290809 How e-mail message formats affect Internet e-mail messages in Outlook
257800 XADM: Winmail.dat Attached to All Internet Messages Regardless of Setting on Client
241538 Description of Transport Neutral Encapsulation Format (TNEF) in Outlook 2000
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Properties

Article ID: 958012 - Last Review: 02/12/2013 05:02:00 - Revision: 9.0

Microsoft Office Outlook 2007, Microsoft Outlook 2010

  • kbfixme kbmsifixme kbqfe kbtshoot kbexpertiseinter kbcip KB958012
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