Applies to Microsoft Outlook 2007 / 2010 / 2013

Under IMAP Setup there is a concept of Subscribed and Unsubscribed folders. The folders that are not visible are presumably those not subscribed

From the left pane of your Outlook; right click the account and select IMAP Folders

Untick the checkbox “When displaying hierarchy in Outlook, show only subscribed folders”

You should now see all folders under your IMAP Account