[KLUG Members] winmail.dat

[Adam Williams]

Well, I found two programs that handle TNEF (which apparently is what 
windmail.dat is).  The first one outputs any text content and writes and 
files to disk,  non-interactive.  The second one (free, not open-source) 
pops up a little window of the contents and which files from inside you 
want to exports.  Tie it to the appropriate MIME type and it integrates 
with evolution very nicely.

tnef2txt
http://www.fiction.net/blong/programs/#tnef2txt

Fentun
http://www.fentun.com/