Java - SSL - Authenticating with gmail's SMTP server

Question

I am able to connect to smtp.gmail.com via port 465. After using the AUTH LOGIN command receive a 334 VXNlcm5hbWU6 which when decoded is "Username:"

I can't seem to figure out how to send my username over the server. I am encoding the username and sending, but getting no reply. The next reply should be to ask for my Password.

See below:

public class MailComponent{
Socket socket = null;
final static String MAIL_SERVER = "smtp.gmail.com";
final static int SMTP_PORT = 465;
String uName = "example@gmail.com";
String encodedName = Base64.getEncoder().encodeToString(uName.getBytes(StandardCharsets.UTF_8));

public MailComponent(){ /*Create constructor later*/}

public void sendMail() throws Exception{

    try{
        // Establish TCP Connection With Mail Server
        socket = ((SSLSocketFactory) SSLSocketFactory.getDefault()).createSocket(MAIL_SERVER, SMTP_PORT);

        // Create a Buffered Reader to read one line at a time
        InputStream inStream = socket.getInputStream();
        InputStreamReader inReader = new InputStreamReader(inStream);
        BufferedReader bReader = new BufferedReader(inReader);

        // Read Server's Greeting
        String serverResponse = bReader.readLine();
        System.out.println("Server Greeting: " + serverResponse);           
        if (!serverResponse.startsWith("220")){
            throw new Exception("220 Reply Not Received From Server!");
        }

        // Reference socket's output stream
        OutputStream oStream = socket.getOutputStream();

        // Send HELO command
        String heloCommand = "HELO smtp.gmail.com\r\n";
        oStream.write(heloCommand.getBytes("US-ASCII"));
        serverResponse = bReader.readLine();
        System.out.println("HELO Response: " + serverResponse);
        if (!serverResponse.startsWith("250"))
            throw new Exception("250 Reply Not Received From Server!");

        // Obtain Authorization
        String authCommand = "AUTH LOGIN\r\n";
        oStream.write(authCommand.getBytes("US-ASCII"));
        serverResponse = bReader.readLine();
        System.out.println("Auth Response: " + serverResponse);

        // Give Username
        oStream.write(encodedName.getBytes(StandardCharsets.UTF_8));    
        serverResponse = bReader.readLine();
        System.out.println("Username Response: " + serverResponse);

Everything seems to work fine, but I don't receive any reply once I send my username. Any ideas on why this might be?

Answer 1

连接到Outlook.com或Office 365 SMTP服务器时，必须在端口587上使用TLS-否则，它们将不接受连接。

Answer 2

Once asked for the username, you must send it encoded as well as sending the CR/LF as Dmitry Streblechenko added in his last comment. However, If you send a username along with the CL/LF the server will think it is part of the username or password and continue waiting for client response. I got it to work by simply sending both in separate messages.

As a note: The STARTTLS command wasn't necessary as I am using SSL.