Using a Draft of a Message
  Choose Include Draft File...  from the Create-Send window's
  File menu to continue working on a message you previously
  saved.
  To resume work on a draft message:
  1.  Choose Include Draft File...  from the Create-Send
      window's File menu.
      A dialog box is displayed in which your draft files are
      listed.
  2.  Click on the name of a draft file.
      The file name is displayed in the Selection entry box.
  3.  Click on the OK button.
  The draft message is displayed in the Create-Send window,
  where you can continue working on it.
  Additional topics:
  *   Saving a Draft of a Message