public class EmailService {

  private String HOST = "imap.gmail.com";
  private String USERNAME = "mail@gmail.com";
  private String PASSWORD = "pass";
  private Properties properties;
  private Store store;
  private Folder inbox;

  public EmailService() throws MessagingException {
    this.properties = new Properties();
    this.properties.put("mail.imap.host", HOST);
    this.properties.put("mail.imap.port", "993");
    this.properties.put("mail.imap.starttls.enable", "true");
  }

  public void openEmailSession() throws MessagingException, InterruptedException {
    Session emailSession = Session.getInstance(this.properties);
    this.store = emailSession.getStore("imaps");
    this.store.connect(HOST, USERNAME, PASSWORD);

    this.inbox = this.store.getFolder("INBOX");
    this.inbox.open(Folder.READ_WRITE);
  }

  public void closeEmailSession() throws MessagingException, IOException {
    this.inbox.close(true);
    this.store.close();
  }

  public Message[] getUserMessages() throws MessagingException, IOException {
    Message[] messages = this.inbox.getMessages();
    return messages;
  }

  public void cleanInbox() throws IOException, MessagingException {
    Message[] messages = this.getUserMessages();
    for (Message message :messages) {
      message.setFlag(Flags.Flag.DELETED, true);
    }
  }
}

emailService.openEmailSession();
emailService.cleanInbox();
emailService.closeEmailSession();