public static String regain(List<Mail> mailList,String filename) throws IOException{
		File mfile = new File(filename);	
		if(!mfile.exists()) return "޼¼";

		Mail aMail = null;
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream(mfile));		
		try{
			while((aMail=(Mail)ois.readObject())!=null){
				mailList.add(0, aMail);
			}
		}catch(EOFException e){
			System.out.println("ļȡ");
		} catch (ClassNotFoundException e) {
			System.out.println("ʽ");
			e.printStackTrace();
		}
		ois.close();
		return "ѯ";
	}