I know when you delete a message in Outlook, they really aren't. The question is, how do you retrieve these deleted emails and import it into a new Outlook install? Haven't reformatted yet, so those messages are somewhere in my computer.
More aboutretrieve deleted emails outlook
Unfortunately, unless you're using business email and your company helpfully stores copies of your email for later perusal, you're in luck. Usually though when Outlook deletes emails they're destroyed for good once you exit the program.