function validacampos (formulario) {
  reEmail = /^[0-50a-z_\-\.]+@[0-50a-z_\-\.]+\.[a-z]{2,3}$/i;

  if (formulario.selcontacto.selectedIndex <= 0) {
    alert ('Non especificou o destinatario do aviso.');
  }
  else {
    if (formulario.email.value.length == 0) {
      alert ('Non introduciu o seu email');
    }
    else {
      if (!reEmail.test(formulario.email.value)) {
	alert ("Debe introducir un email correcto.");
      }
      else {    
        if (formulario.corpo.value.length == 0) {
          alert ('Non escribiu a mensaxe.');
        }
        else {
          formulario.submit();
        }
      }
    }
  }
}

function borrarcampos (formulario) {
  formulario.selcontacto.selectedIndex = 0;
  formulario.email.value = '';
  formulario.asunto.value = '';
  formulario.corpo.value = '';
}