Handle socket errors

lib/ping_services/smtp.js

@@ -9,7 +9,10 @@ function ping (service, callback){
   socket.on("data", function (c) {
     socket.end("bye!");
   });
-
+
+  socket.on("error", function () {
+	callback("Could not open socket", null, null, null);
+  });
   socket.on("end", function () {
     var timeDiff = (new Date() - startTime);
     callback(null, null, null, timeDiff);