No problem here...email works fine. My server is webmail.[domain name]. If you have touchdown, maybe you can compare the settings in TD to see if they're the same in the native app.
With that being said, my one big beef with the native app is that it only sync's at the most one month's worth of email. So, I still use TD for my email. My wife's HTC Incredible with their Sense email allows her to sync ALL of her email.