Here is a nice full featured email client that runs on its own, you can just copy it to a USB stick.
http://www.xtort.net/office/floppyoffice.php
(Scroll down and download the "Floppy Office" set of programs. When there, grab the zip folder that says something like "npopwin32" and unzip the program and the readme to your usb stick.)
John-
just put a link and a write-up to this in the Internet section. Thanks!