I too have just recently started having this problem whereas I didn't before.
My work uses O2003 whilst my home PC is using O2007. Definitely not OExpress.
It is rather strange because I have sent various emails from work with
different attachments - XLS, PPT, DOC and they all end up embedded in an
attachment titled "originalemail.eml".
The extra weird thing is that the received email includes the companies
copyright autosignature on the bottom, but none of my text above it.
So I did a test where I set up a redirect of the email on my ISP account
straight back to work. When I checked it as webmail, no problems and it
arrived at work all OK. However at home it arrived embedded.
So my conclusion is its something to do with my O2007
Can anyone shed more light?
Rod