Use xSocket BlockingConnection

xSocket
License: LGPL - Lesser General Public License

// -- Main.java --
import org.xsocket.connection.BlockingConnection;
import org.xsocket.connection.IBlockingConnection;

public final class Main {

  private static IBlockingConnection connection = null;

  public static void main(String... args) throws Exception {
    connection = new BlockingConnection("mailserver.hostname", 25);
    try {
      cmd(null, 220);
      cmd("HELO mailserver.hostname", 250);
      cmd("MAIL FROM:lance", 250);
      cmd("RCPT TO:solnone NOTIFY=success,failure", 250);
      cmd("DATA", 354);      
      cmd("Subject: Test Mail use telnet\r\n\r\nJust test.\r\n.\r\n", 250);

      connection.write("QUIT\r\n");
    } finally {
      if (connection != null) {
        connection.close();
      }
    }

  }

  private static void cmd(String cmd, int replyCode) throws Exception {
    if (cmd != null) {
      connection.write(cmd + "\r\n");
    }
    String line = connection.readStringByDelimiter("\r\n").trim();
    System.out.println(line);
    if (!line.startsWith(Integer.toString(replyCode))) {
      throw new Exception("Error reply code");
    }
  }
}