As long as the email is not digitally signed, you can
never be sure who
sent you the email, and you shouldn't really rely on the outgoing mail
server.... (hint: check this email's mail server)
Now what's the problem ;-) I looked at your mail header and learned the
following:
The recieving mail server (mxng06.kundenserver.de) got this mail from
tri-e2k.ethz.ch [129.132.112.23]. Now this mail server is not
responsible for
yahoo.com. Conclusion: From address faked, mail
discarted (No, not yet. I read your mail, thanks to the freedoms we
still have).
If you want to be discarted today you can use the adress
thibritz(a)fuba.lu, because fuba.lu is not DNS resovable. 10 years ago we
didn't even have this freedom restriction ;-)
Greeting, Patrick Kaell