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Problems with viewing TNEF messages

How do I extract the TNEF data (winmail.dat) using Outlook Express?

Outlook Express has the bad habit of hiding TNEF data leaving no direct way of extracting it from the mail. This is what Outlook Express shows when opening mails containing TNEF:


TNEF mail shown as empty


Follow this procedure carefully to work around this problem:

  1. From Outlook Express save the mail to disk using the File | 'Save As...' menu option.


  2. Open the *.eml file in a binary editor. If you use notepad you will almost certainly corrupt the mail!!

    Editing TNEF Content Type

  3. Identify the text Content-Type: application/ms-tnef; and edit this to Content-Type: application/ms-tnex; 


  4. Save Changes and open the mail in Outlook Express again. You will now get the typical message:
    "OE removed access to the following unsafe attachment in your mail: winmail.dat"


  5. Hit the forward button of the mail and the winmail.dat will be available for you to access.

    Saving winmail.dat attachment

  6. Just drag and drop the winmail.dat attachment to windows explorer in order to extract the attachment.


When opening a TNEF message I am unable to view any message properties. The viewer just shows the Headers node with a red cross next to it. What is wrong?

Corrupt TNEF data

This happens when the TNEF file being opened is corrupted. Most commonly the corruption occurs on extracting TNEF from mime mails, this is a bit tricky with Outlook Express. 

Try opening different TNEF files and see whether the problem is specific to a single winmail.dat or to all TNEF. If you are not convinced a TNEF file is corrupted, mail this to (check 'Feedback and Support' for more details).


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Problems with viewing Outlook *.msg files

I am unable to open MS Outlook messages with the viewer. When attempting to open a message the following dialogs are shown. What is the problem?

Set Outlook as default client

MAPI Initialization Failure

Check the following:

  1. Make sure that Microsoft Outlook or some other type of MAPI client is correctly installed i.e. you can send and receive mails without problems.
  2. In case of Outlook make sure it is not configured in Internet Mail Only mode. In this mode Outlook behaves as an SMTP/POP3 client and you won't be able to use the viewer.
  3. Check that the Outlook client is configured as the default mail client. Check this from Internet Explorer settings under: 
    Tools | Internet Options... | Programs | Email 


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