class method self.mkfinal

# File actionmailer/lib/action_mailer/vendor/tmail-1.2.7/tmail/mailbox.rb, line 248
    def UNIXMbox.mkfinal( mh, mboxfile, writeback_p, cleanup_p )
      lambda {
          if writeback_p
            lock(mboxfile) {|f|
                mh.each_port do |port|
                  f.puts create_from_line(port)
                  port.ropen {|r|
                      f.puts r.read
                  }
                end
            }
          end
          if cleanup_p
            Dir.foreach(mh.dirname) do |fname|
              next if /\A\.\.?\z/ === fname
              File.unlink "#{mh.dirname}/#{fname}"
            end
            Dir.rmdir mh.dirname
          end
      }
    end