Ошибка Connection reset протокол SMTP

Есть простой SMTP клиент, который лишь должен отправлять команды на сервер SMTP и получать код ответа и сообщение. Все бы ничего, но по какой-то причине дальше команды STARTTLS клиент отказывается работать с ошибкой Connection reset. В чем может быть ошибка? Привожу ниже код:

import java.net.*;
import java.io.*;
import java.util.Objects;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;

public class EmailClient {
    public static void main(String[] args) {
        String host = "smtp.gmail.com";
        int port = 587;
        String from = "[email protected]";
        String to = "[email protected]";
        String subject = "Test email";
        String body = "This is a test email.";

        try {
            // Create a socket connection to the mail server
            Socket socket = new Socket(host, port);
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintWriter out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));

            // Read the server's greeting
            String response = in.readLine();
            System.out.println(response);

            // Send the EHLO command to initiate the SMTP conversation
            out.println("EHLO " + host);
            out.flush();

            do {
                response = in.readLine();
                System.out.println(response);

            }while (!Objects.equals(response, "250 SMTPUTF8"));

            // Start a secure TLS connection
            out.println("STARTTLS");
            out.flush();
            response = in.readLine();
            System.out.println(response);

            SSLSocketFactory sslSocketFactory = (SSLSocketFactory) SSLSocketFactory.getDefault();
            SSLSocket sslSocket = (SSLSocket) sslSocketFactory.createSocket(socket, host, port, true);

            in = new BufferedReader(new InputStreamReader(sslSocket.getInputStream()));
            out = new PrintWriter(new OutputStreamWriter(sslSocket.getOutputStream()));


            // Set the sender and recipient of the email
            out.println("MAIL FROM:<" + from + ">");
            out.flush();
            response = in.readLine();
            System.out.println(response);

            out.println("RCPT TO:<" + to + ">");
            out.flush();
            response = in.readLine();
            System.out.println(response);

            // Send the email content
            out.println("DATA");
            out.flush();
            response = in.readLine();
            System.out.println(response);

            out.println("Subject:" + subject);
            out.println("");
            out.println(body);
            out.println(".");
            out.flush();
            response = in.readLine();
            System.out.println(response);

            // Close the connection
            out.println("QUIT");
            out.flush();
            response = in.readLine();
            System.out.println(response);

            socket.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}