var subscribe = function(sub_email) {
   var opt = {
      method: 'post',
   	  postBody: 'sub_email=' + sub_email + '&r=' + Math.random(),
   	  onSuccess: function(t) {
         var response = t.responseText.split(':');
         alert(response[1]);
   	  },

   	  onLoading: function() {
   	  },

   	  on404: function(t) {
         alert('Error 404: location "' + t.statusText + '" was not found.');
   	  },

   	  onFailure: function(t) {
         alert('Error ' + t.status + ' -- ' + t.statusText);
   	  }
   }
   new Ajax.Request('subscribe.php', opt);
}

var evalResponse = function(request) {
    try {
        return eval('('+request.responseText+')');
    } catch (e) {}
}