How to get sa-learn the original message of application/ms-tnef email?

[Christian Purnomo <cp...@cpurn.net>]

Hello All.

We have a smarthost running spamassassin in the permiter, this host
relays email for our internal domains to an M$ Exchange server in our
private LAN.   Spamassassin is doing a great job in filtering most
spams.  

I get my MS Exchange users to drop any 'Undetected SPAM' to a folder
which I daily feed to sa-learn on the smarthost.  I can notice a big
difference this makes to the spamassassin filter.  After a time, I
notice an email pattern in this folder that doesn't seem to improve from
time to time.

I did some investigations and concluded that most emails with ms-tnef
have low rate spam detection.  My guess is that because the emails that
I feed to sa-learn is NO LONGER the original email due to ms-tnef.
Below is a sample email from my Undetected Spam folder, as you can see,
the mail body gets modified, hence sa-learn do not get to learn the
original message and this kind of spam pattern just keeps coming in.

I read a bit about ms-tnef on this website 
http://agamemnon.ucs.ed.ac.uk/faq/mstnef.html - I can't get my Exchange
server to receive text only message (instead of rich text/html) due to
internal politic issue, so I'm trying to find a way to get around this
outside the Exchange box.

Has anyone experience this problem before? 

Thanks in advance.





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