Java by API/javax.mail/Authenticator

extends Authenticator

 
import java.util.Properties;
import javax.mail.Authenticator;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Store;
public class Main {
  public static void main(String[] args) throws Exception {
    Properties props = new Properties();
    String host = "yourserver.edu";
    String provider = "pop3";
    Session session = Session.getDefaultInstance(props, new MailAuthenticator());
    Store store = session.getStore(provider);
    store.connect(host, null, null);
    Folder inbox = store.getFolder("INBOX");
    if (inbox == null) {
      System.out.println("No INBOX");
      System.exit(1);
    }
    inbox.open(Folder.READ_ONLY);
    Message[] messages = inbox.getMessages();
    for (int i = 0; i < messages.length; i++) {
      System.out.println("Message " + (i + 1));
      messages[i].writeTo(System.out);
    }
    inbox.close(false);
    store.close();
  }
}
class MailAuthenticator extends Authenticator {
  public MailAuthenticator() {
  }
  public PasswordAuthentication getPasswordAuthentication() {
    return new PasswordAuthentication("username", "password");
  }
}