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.
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:
Add the DisableTNEF registry entry. To do this, follow these steps:
Exit Outlook 2010.
Start Registry Editor.
In Windows 7, click Start , type regedit in the Search programs and files box, and then press Enter.
In Windows Vista, click Start, type regedit in the Start Search box, and then press Enter.
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, and then click OK.
Locate and then select the following registry subkey: