You can use Outlook’s New->Folder menu option to create a folder that contains journal, note, task, or mail items. These items in any newly created folder are stored on the mail server.
The items in the default Journal and Notes folders are stored on the mail server. The items in the default Calendar, Tasks, and Contacts folders are stored in the calendar server (Calendar and Tasks) and address book server (Contacts). No subfolders may be created under the default Calendar, Tasks, or Contacts.