Kita cukup membuat 1 class java saja.
1. CheckingMails
CheckingMails.java import java.util.Properties;
import javax.mail.Address;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.Session;
import javax.mail.Store;
public class CheckingMails {
    public static void check(String host, String storeType, String user, String password) {
        try {
            Properties properties = new Properties();
            properties.put("mail.pop3.host", host);
            properties.put("mail.pop3.port", "995");
            properties.put("mail.pop3.starttls.enable", "true");
            Session emailSession = Session.getDefaultInstance(properties);
            Store store = emailSession.getStore("pop3s");
            store.connect(host, user, password);
            Folder inbox = store.getFolder("INBOX");
            inbox.open(Folder.READ_ONLY);
            Message[] messages = inbox.getMessages();
            System.out.println("Message all : " + messages.length);
            for (int i = 0; i < messages.length; i++) {
                Message message = messages[i];
                System.out.println("---------------------------------");
                System.out.println("Email Number : " + (i + 1));
                System.out.println("Time : " + message.getSentDate());
                System.out.println("Subject : " + message.getSubject());
                System.out.println("From: " + message.getFrom()[0]);
            }
            inbox.close(false);
            store.close();
        } catch (NoSuchProviderException e) {
            e.printStackTrace();
        } catch (MessagingException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
      String host = "pop.gmail.com";//server mail
      String mailStoreType = "pop3";
      String username = "yourmail@mail.com";
      String password = "your password mail";
      check(host, mailStoreType, username, password);
    }
}
Output :
 
 









