Mail Moves Messages

Hi -

To make a long story short - my house burnt down and I bought a new MacBook Pro running Lion. On my old iMac I used the mail application and so I naturally use it on my new MacBook Pro. I can send and receive message easily but whenever I reply or forward to a message Mail moves it out of the Inbox and to the sent folder. So if I want to go back to the message I have to go into the sent folder. How do I keep them in the inbox and not have them automatically move. On my iMac this never happened (I was running Lion on it too.) Any help is appreciated!

Spencer