function objetoAjax(){
  var xmlhttp=false;
  try {
  xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
  } catch (e) {
  try {
  xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
  } catch (E) {
  xmlhttp = false;
  }
  }
  if (!xmlhttp && typeof XMLHttpRequest!='undefined') {
  xmlhttp = new XMLHttpRequest();
  }
  return xmlhttp;
}

function enviar_em(def) {
	objeto = document.getElementById('NewsEmail');
	var email = objeto.value;
	
	if ((email != '') && (email != def)) {
		ajax=objetoAjax();
	
		ajax.open("POST", "enviar_mail.php");
		ajax.onreadystatechange=function() {
			if (ajax.readyState==1) 
			{ 
				objeto.value = "Envoi..."; 
				objeto.disabled = true;
			} 
			else if(ajax.readyState==4) 
			{ 
				if(ajax.status==200) 
				{ 
					res = ajax.responseText;
					if (res == "true") {
						objeto.value = "";
					} else {
						objeto.value = "Erreur en envoyant";
					}
				} 
				else 
				{ 
					objeto.value = "Erreur: "+ajax.status; 
				} 
				objeto.disabled = false;
			} 
		}

		ajax.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
		ajax.send("email=" + email);
	}
}