function valida_pop() {
  var form = document.frmCadastro;
  if (form.nome_news.value == '') {
    alert('Digite seu nome');
    form.nome_news.focus();
    return false
  }
  if (validaemail(form.email_news.value) == false) {
    alert('Digite o email corretamente');
    form.email_news.focus();
    return false
  }
  return true
}

function validaemail(email) {
  var objRegExp  = /^[A-Za-z]([\w\.]*)@([A-Za-z0-9\.]*)\.(([A-Za-z]{3}\.[A-Za-z]{2}$)|([A-Za-z]{3}$)|([a-z]{2}$))/i ;
  return objRegExp.test(email);
}