public static String receive(User user,List<Mail> mailList)throws IOException{
		int mCount = 0;
		String response = "";
		
		Socket s = new Socket(user.getPopServer(),110);
		
		BufferedReader inFromServer = new BufferedReader(
				new InputStreamReader(s.getInputStream()));
		PrintWriter outToServer = new PrintWriter(
				new OutputStreamWriter(s.getOutputStream()));
		response = inFromServer.readLine();
		System.out.println(response);
		if(response.indexOf("+OK")==-1) return "޷ӷ";
		
		response = exchange("user "+user.getUsername(), inFromServer, outToServer);
		System.out.println(response);
		if(response.indexOf("+OK")==-1) return "û";
		
		
		response = exchange("pass "+user.getPassword(), inFromServer, outToServer);
		System.out.println(response);
		if(response.indexOf("+OK")==-1) return "";
		
		
		response = exchange("list", inFromServer, outToServer);
		System.out.println(response);
		if(response.indexOf("+OK")==-1) return "޷ʼ";		
		for(mCount=0;!".".equals(response=inFromServer.readLine());mCount++){
			System.out.println(response);
		}
		MailDecoder mDecoder = new MailDecoder();
		List<Mail> keptList = new ArrayList<Mail>();
		
		regain(keptList, "user/"+user.getUsername()+"/recvBox.dat");
		int downCount = 0;
		for(int i=1;i<=mCount;i++){
			StringBuffer original = new StringBuffer();
			response = exchange("retr "+i, inFromServer, outToServer);
			if(response.indexOf("+OK")==-1) continue;
			response = inFromServer.readLine();
			while(!".".equals(response)){
				original.append(response+"\n");
				response = inFromServer.readLine();
			}
			Mail aMail = new Mail();
			
			MailClient.stateTextArea.setText(""+mCount+
					"ʼ\nص"+i+"ʼ...");		
			
			mDecoder.packMail(aMail, original.toString());
			Iterator<Mail> it = keptList.iterator();
			int j=0;
			for(;it.hasNext();j++){
				if(aMail.equals(it.next())) break;
			}
			if(j==keptList.size()){//ļ޸ü¼
				save(aMail,"user/"+user.getUsername()+"/recvBox.dat");
				mailList.add(aMail);
				downCount++;
			}
			
		}
		response = exchange("quit", inFromServer, outToServer);
		System.out.println(response);
		s.close();
		
		return "ɹ"+downCount+"ʼ";
	}