code:
function OnEvent_ContactSignin(sEmail){
var ChatWnd_obj = Messenger.OpenChat('your email here');
if (ChatWnd_obj.EditChangeAllowed == true){
ChatWnd_obj.SendMessage(sEmail+' is online');
ChatWnd_obj.Close(0);
}
else{
ChatWnd_obj.Close(0);
}
}
Something like this, however Mobile messages ARE different from normal messages as microsoft has now added offline messages.