function validateSubscribeForm(f) {
    if (f.email_address.value == "") {
      alert("Please enter your email address");
      f.email_address.focus();
      return false;
    }

    if (isEmail(f.email_address.value) == false) {
      alert("Please enter a valid email address (e.g. yourname@yourcompany.com.au)");
      f.email_address.select();
      return false;
    }

    return true;
  }

  function isEmail(string) {
    return (string.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) != -1)
  }