import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;

public class SMTPServer {
    public static void main(String[] args) {
        while (true) {
            try (ServerSocket serverSocket = new ServerSocket(25)) {
                Socket client = serverSocket.accept();
                System.out.println("Accepted!");
                BufferedReader clientIn = new BufferedReader(new InputStreamReader(client.getInputStream()));
                BufferedWriter clientOut = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
                clientOut.write("220 OK\r\n");
                clientOut.flush();
                String inputLine;

                char[] buffer = new char[1024];
                int count;
                while ((count = clientIn.read(buffer)) != -1) {
                    System.out.println(buffer);
                    clientOut.write("250 OK\r\n");
                    clientOut.flush();
                }

                clientOut.write("250 OK\r\n");
                clientOut.flush();

                inputLine = clientIn.readLine();
                System.out.println(inputLine);
                inputLine = clientIn.readLine();
                System.out.println(inputLine);
                inputLine = clientIn.readLine();
                System.out.println(inputLine);
                inputLine = clientIn.readLine();
                System.out.println(inputLine);
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
        }
    }
}