I use
Mail.app for my e-mail client. It usually display everything right, but it will choke on some non standard code or if the sender forgets to close a tag, basically the same problems that Netscape would have.
It uses the rendering engine KHTML from the KDE open source project, same as
Safari.
As far as I know all the mails have displayed properly except for the one where you tried to include the code for tables, the code just displayed as an empty table, just white space.