This changes things from the original post.
I don't know of any process/program that could do this by itself, including
Word as mirrored images are generally a product of the printing process.
You may be able to print to a PDF file as a mirror image and then send that
file as an Outlook Express attachment. I know that Adobe Acrobat version 6
does not have the capability of mirroring output but other PDF writers may
be able to do that.
Does the "file" to be created need to be editable at the destination end?
If not and the document will fit on one screen page, you could also "screen
capture" the image, put it into a picture/photo editor and mirror the image,
and send that image as a file attachment. For screen captures I use a free
software product called Screen Hunter 4 free from this web site
http://www.wisdom-soft.com/products/screenhunter_free.htm which will allow
you to set the program to capture just what is selected using the mouse. I
find this very useful. If you save the captured image to the clipboard you
can import the image into MS Paint and reverse the image there by Pasting
the clipboard into the program, clicking Image/Flip-Rotate/Flip Horizontal
then save the image to attach.
Curiosity has now gotten the better of me. Why do you need to send this
file as a mirrored image? Could the recipient not mirror the output when
the job is printed at the other end?