Opening a Folder in a New Window (Paned Style)

  If you are using a Paned style main window, choose Open
  Folder In New Window from the main window's File menu
  to open the selected folder in a new main window.  The
  messages in the open folder are listed in the message pane of
  the new main window.

  Opening a new main window lets you have different folders
  open at the same time.  You can perform all Mail tasks on the
  drawers, folders, and messages displayed in the new window.

  For information about the different main window styles,
  double click on the additional topic below.

  Additional topics:

  *   Options Menu