// change your domain name:
var yourURL = "http://www.trentinosalumi.it/";

function outLinks() {
  var outLink;
  if (document.getElementsByTagName('a')) {
    for (var i = 0; (outLink = document.getElementsByTagName('a')[i]); i++) {
      if (outLink.href.indexOf(yourURL) == -1) {
        outLink.setAttribute('target', '_blank');
      }
    }
  }
}

var oldEvt = window.onload;
window.onload = function() { 
					if (oldEvt) oldEvt(); 
					outLinks(); 
				}