public static boolean checkUser(String user) {
		Socket serverSocket = null;
		try {
			serverSocket = new Socket(MailServer.serversIPTable.get(user.split("@")[1]), 1500);
			BufferedReader in = new BufferedReader(new InputStreamReader(serverSocket.getInputStream()));
			PrintWriter out = new PrintWriter(serverSocket.getOutputStream(),true);
			
			out.println("CHECK CONTACT " + user);
			return in.readLine().startsWith("OK CHECK CONTACT");
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				serverSocket.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return false;
	}