function valid(email)
{
  quote = '"'
  invalidChars = quote+" /:,;[]()<>'";

  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("@", 1);
  if (atPos == -1) {
    return false;
  }
  if (email.indexOf("@", (atPos + 1)) > -1) {
    return false;
  }
  periodPos = email.indexOf(".", atPos);
  if (periodPos == -1) {
    return false;
  }
  if ((periodPos + 3) > email.length) {
    return false;
  }
  return true;
}