Email help for a newbie

Hi there... totally new to blackberrys and I have a 9000.. received today. The email is all working ok and I receive them on the blackberry. But when I then receive them when I go online via my pc.. they disappear from the blackberry. Is this normal or do I have something set up wrong.

AH... I think I might have sorted it out

Welcome to CrackBerry.

Isn't that always the way, right after you figure out the right question to ask, the answer presents itself. ;)

I might help other with the same problem if you can provide an answer too.