Mozilla Thunderbird

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The Microsoft Outlook e-mail program sometimes sends e-mails in the Transport Neutral Encapsulation Format (TNEF). Most other e-mail programs, including Thunderbird, do not understand TNEF.

If your e-mail program doesn't understand TNEF, instead of seeing the e-mail and/or attachment, you may only see an attachment named "winmail.dat" or "Part 1.2" that you cannot open. Also, sometimes you may receive a TNEF attachment with a generic name such as ATT00008.dat or ATT00005.eml instead.

You can configure Thunderbird to use one of the programs below to open the TNEF attachment.

• Winmail.dat Reader Windows 95X though Windows Server 2003
• Fentun Win9X, NT, Win2K and WinXP
• AkeeSoft WMViewer Windows 95X though Windows Server 2003
• Winmail Opener Windows 95X though Windows Server 2003
• TNEF Linux
• TNEF's Enough OS9 and OSX

On Windows XP:

1. Download and install either Winmail.dat Reader, Fentun, AkeeSoft WMViewer, or Winmail Opener.
2. Open Thunderbird
3. Find an email with a Winmail.dat attachment
4. Double-click on Winmail.dat attachment
5. A “Opening Winmail.dat“ dialog box will pop up
6. Select “Open with“
7. Click on Browse, then simply browse to wherever you installed the program (For example, c:\Program Files\Fentun\fentun.exe)
8. Tick the checkbox that says “Do this automatically for files like this from now on“