Default email client keeping messages

[Paula Popper]

I have a Motorola Atrix HD (obviously, posting in this forum). I have used the default/stock email client, but don't love it so much. However, even though I have it syncing with the server on my POP3 account, it retains ALL messages (except for those I manually delete), even when the server's messages have been downloaded/offloaded to my PC for permanent storage, etc. So the server no longer has all the messages. But the default email client on my phone does. To the tune of 800+MB of messages. I need to get these off, and I'm not sure what do do. I'd rather be using a different email client on my phone, but am not sure what that should be. Once I'm using something else, if I delete the profile from the default email client (or through the apps section of settings) will these all go away?

thanks!
Paula