Online Archive is a separate mailbox that appears in Outlook (on left) that looks like how a .pst would look when attached. The Archive would have greater storage limits (50GB right now). The archive’s back end location could be on a separate database or even in the cloud. This is an alternative to storing a local .pst file. Emails can be added to the Personal Archive mailbox by dragging and dropping from your normal mailbox
Once Online Archive is activated for your account, you will be prompted to re-enter your password.