public static void save(List<Mail> mailList,String filename) throws IOException{
		if(!(mailList.size()>0)) return ;
		File mfile = new File(filename);
		if(!mfile.exists()) mfile.createNewFile();
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(mfile));
		for(Iterator<Mail> it=mailList.iterator();it.hasNext();)
			oos.writeObject(it.next());
		oos.flush();
		oos.close();
	}