Java手动实现SMTP邮件发送：EHLO与AUTH PLAIN认证详解

echo -ne '000your_username000your_password' | openssl base64

echo -ne '000test@naver.com000mysecretpassword' | openssl base64

import java.util.Base64;  // ... String username = "your_username@example.com"; String password = "your_password"; String authString = "00" + username + "00" + password; String encodedAuthString = Base64.getEncoder().encodeToString(authString.getBytes()); // ...

import javax.net.ssl.SSLSocketFactory; import javax.net.ssl.SSLSocket; import java.io.*; import java.net.*; import java.util.Base64; // 引入Base64类  class MailServer {      // 请替换为你的实际邮箱用户名和密码     private static final String USERNAME = "your_username@naver.com";     private static final String PASSWORD = "your_password";      public static void MailSender() throws Exception {         String Reply;         String To = "recipient@example.com"; // 收件人邮箱         String From = USERNAME; // 发件人邮箱，通常与认证用户名一致         String Data = "Subject: Hello from Java SMTP ClientrnrnHello this is computer networking."; // 邮件内容，包含Subject和空行          SSLSocketFactory sslsocketf = (SSLSocketFactory) SSLSocketFactory.getDefault();         System.out.println("Connect Start");         // 连接到SMTP服务器的SSL端口，通常是465         SSLSocket socket = (SSLSocket) sslsocketf.createSocket("smtp.naver.com", 465);         System.out.println("Connect Success");          BufferedReader inFromServer = new BufferedReader(new InputStreamReader(socket.getInputStream()));         PrintWriter outToServer = new PrintWriter(socket.getOutputStream(), true);          // 接收服务器的初始欢迎信息         Reply = inFromServer.readLine();         if (Reply.startsWith("220")) {             System.out.println("Server Connect Success!");         } else {             System.out.println("Server Connect Fail");             System.exit(0);         }         System.out.println(Reply);          // EHLO命令 - 替换HELO，获取服务器扩展功能         outToServer.println("EHLO naver.com"); // 使用你的域名或IP地址         Reply = inFromServer.readLine();         ReplyCheck(Reply, "250"); // 检查EHLO响应          // AUTH PLAIN命令 - 进行身份认证         String authString = "00" + USERNAME + "00" + PASSWORD;         String encodedAuthString = Base64.getEncoder().encodeToString(authString.getBytes("UTF-8")); // 指定UTF-8编码         outToServer.println("AUTH PLAIN " + encodedAuthString);         Reply = inFromServer.readLine();         ReplyCheck(Reply, "235"); // 235表示认证成功          // MAIL FROM command         outToServer.println("MAIL FROM: <" + From + ">");         Reply = inFromServer.readLine();         ReplyCheck(Reply, "250");          // RCPT TO command         outToServer.println("RCPT TO: <" + To + ">");         Reply = inFromServer.readLine();         ReplyCheck(Reply, "250");          // DATA command         outToServer.println("DATA");         Reply = inFromServer.readLine();         ReplyCheck(Reply, "354"); // 354表示可以开始发送邮件内容         outToServer.println(Data);         outToServer.println("."); // 邮件内容结束标志         Reply = inFromServer.readLine(); // 读取DATA命令后的响应         ReplyCheck(Reply, "250"); // 250表示邮件接受成功          // QUIT command         outToServer.println("QUIT");         Reply = inFromServer.readLine();         ReplyCheck(Reply, "221"); // 221表示服务器关闭连接          outToServer.close();         inFromServer.close();         socket.close();     }      public static void ReplyCheck(String Reply, String Status) throws Exception {         System.out.println(Reply);         if (!Reply.startsWith(Status)) {             throw new Exception(Reply);         }     }      public static void main(String args[]) {         try {             MailServer.MailSender();             System.out.println("Send Mail Success!");         } catch (Exception e) {             System.out.println("Send Mail Fail");             System.out.println(e.toString());         }     } }