# File lib/action_mailer/vendor/tmail-1.2.3/tmail/mailbox.rb, line 237
    def initialize( fname, mhdir, readonly, static )
      @filename = fname
      @readonly = readonly
      @closed = false

      Dir.mkdir mhdir
      @real = MhMailbox.new(mhdir)
      @finalizer = UNIXMbox.mkfinal(@real, @filename, !@readonly, !static)
      ObjectSpace.define_finalizer self, @finalizer
    end