UNIX->Exchange Outgoing Email Address Munged

[Randy Yates]

I gnus within xemacs to compose and send my corporate mail to the
Microsoft Exchange server.

Everything functions correctly. The problem is that Exchange "munges"
the "From" address in outgoing email messages to:

  From: us057845@usrts005.corpusers.net
  [mailto:us057845@usrts005.corpusers.net] On Behalf Of Randy Yates

instead of just simply "Randy Yates" as I am listed in the corporate 
Outlook phonebook. 

I'd like to change this so that my "From" address looks normal. How
can I do this? How does Exchange know whether the client is Outlook
or my unix mail client? 
-- 
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124