Unless the email has a "open in brower" option (some do), I'm not sure how you can spawn the message in a browser easily.
FlexMail and ProfiMail are two that I know of. I have used both. FlexMail has a much better interface and fully integrates with SMS. It does in fact render HTML better. ProfiMail has better IMAP support in some cases. Both offer trials.
FlexMail:
http://webis.net/products_info.php?p_id=mail
ProfiMail:
http://www.lonelycatgames.com/?app=profimail
Enjoy...