MS Outlook Question

[sandmtrailboss]

I've got a freind who runs a small online buisness and he gets a ton of e-mails each day. He doesnt want to lose all this e-mail because alot of them have important information. He bought a 20 gig external hd for back-up. He uses Outlook for all his e-mail. This is the part the stumps me, when you look and his earthlink account threw Outlook (hes on 56k) he can see all the messages he gets, but when he logs onto his earthlink account threw a browser it only shows a couple miscellaneous e-mails that dont relate to anything. My question is, is outlook downloading the e-mail form his earthlink account and deleting it? If so I want to find the folder where it is stored on his computer so we can back it up. Thanks for any help!