code: public static String domain2ns(String id) {
  		int at = id.indexOf('@');
  		if (at >= 0) {
  			String[] domain = id.substring(at + 1).split("\\.");
  			StringBuilder ns = new StringBuilder(id.length());
  			boolean first = true;
  			for (int i = domain.length - 1; i >= 0; --i) {
  				if (first) {
  					first = false;
  				} else {
  					ns.append('.');
  				}
  				ns.append(domain[i]);
  			}
  			return ns.toString();
  		} else {
  			return "";
  		}
  
  	}
docs: Translate an ID into it's domain
  
  i.e. myid1234@myapp.att.com results in domain of com.att.myapp
  
  @param id
  @return