Problem with Thunderbird

David Harrison dharrison at
Wed May 16 18:21:16 UTC 2007

I think I solved the problem just before receiving Fabian's suggestion:

Synaptic Package manager: search for TNEF

Then install: libytnef0-dev

Description below:

improved decoder for application/ms-tnef attachments
Yerase's TNEF Stream Reader allows you to decode application/ms-tnef
e-mail attachments, which are usually entitled "winmail.dat" and are
generally a file container format that is only readable by Microsoft
Outlook. Some TNEF streams also include RTF-formatted data.

libytnef0 is the support library that exposes these functions to other
programs. The ytnef program (and eponymous package) is the frontend for
this library, so you should probably install that if you want to take
advantage of it.

I just sent myself a Word document from a WinXP machine and was able to 
open it: hopefully I have solved my problem. In any case, thnaks to 
Fabian for his suggestions.

Dave Harrison

Fabian Rodriguez wrote:
> David Harrison wrote:
>> [...]My issue: for some reason when MS WOrd 
>> documents are sent to me as file attachments, all I get is a file 
>> attachment called winmail.dat which (a) is not the file attachment that 
>> was sent, and (b) I can't open anyway.
>> However if I send myself a file attacment of an Open Office document, I 
>> can openit properly.
> Outlook and Outlook Express do this. It' s called Transport Neutral 
> Encapsulation Format (TNEF), it's a proprietary attachment format.
>  From :
> "When an Outlook user composes and sends a message using either Rich 
> Text Format or HTML Format, Outlook automagically generates a file, 
> *winmail.dat*, and attaches it to the end of the message. *winmail.dat* 
> contains formatting information, in a human-unreadable form, that 
> Outlook will use on the receiving end to display this email message 
> correctly. Unfortunately, Outlook is the *ONLY* email client program 
> that can use this information! Netscape Messenger, Eudora^* 
> <>, and other 
> email client programs don't understand this information."
> If you think the sender of the problematic email(s) may be receptive to 
> this problem, you can try and have them follow instructions from this MS 
> Knowledgebase article:
> How to Prevent the Winmail.dat File from Being Sent to Internet Users
> There' s also more information here:
> And of course there' s an extension, for those cases where the sender 
> can't or won't cooperate:
> Let us know how /if this works out for you.
> Cheers,
> Fabian Rodriguez

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