    def deliver!(mail)
      if ::File.respond_to?(:makedirs)
        ::File.makedirs settings[:location]
      else
        ::FileUtils.mkdir_p settings[:location]
      end

      mail.destinations.uniq.each do |to|
        ::File.open(::File.join(settings[:location], to), 'a') { |f| "#{f.write(mail.encoded)}\r\n\r\n" }
      end
    end
The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.