Hi, thanks, I know about Fentun, but it's not working. Didn't display any contents in winmail.dat. I read it's sometimes not working on Windows XP so I didn't bother much with it.
FWIW, I wrote a small script to assist me a bit with WMDecode, until I find something better or Thunderbird learns to handle TNEF. I configured Thunderbird to launch it, when I double-click a Winmail.dat attachment.
set dir=C:\Dokumente und Einstellungen\alx.SCALA\Desktop\Winmail.dat Attachments
if not exist "%dir%"\nul md "%dir%"
"%wmd%" "%1" n "%dir%"
start explorer "%dir%"