function validEmail (email) {
      invalidChars = " /:,;"
      if (email=="") { return false }
      for (i=0; i<invalidChars.length; i++) {
        badChar = invalidChars.charAt(i)
        if (email.indexOf (badChar, 0) != -1) { return false }
      }
      atPos = email.indexOf ("@", 0)
      if ((atPos == -1) || (atPos == 0)) { return false }
      if (email.indexOf ("@", atPos+1) != -1) { return false }
      periodPos = email.indexOf (".", atPos)
      if ((periodPos == -1) || (periodPos == atPos+1)) { return false }
      if (periodPos+3>email.length == -1) { return false }
      return true;
}

function zapisz(form) {
	if (!(validEmail(form.email.value))) {
		alert('Podaj poprawny adres e-mail.');
		form.email.focus();
		form.email.select();
		return false;
	}
	else {
		return true;
	}
}