введите сюда код

String mail;
String pass;
String mailSender = "info@e-registry.kiev.ua";

DBHelper dbHelper;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    toolbar.setNavigationIcon(R.mipmap.ic_mob);
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("https://e-registry.kiev.ua"));
            startActivity(browserIntent);
        }
    });

    toolbar.setNavigationOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            finish();
        }
    });

    dbHelper = new DBHelper(this);

    try {
        messages();
    } catch (Exception e) {
        TextView seeMail = (TextView) findViewById(R.id.text_mail);
        String mesMail = "An exception";
        seeMail.setText(mesMail);
    }
}
    public void messages() throws Exception {

    int smtpPort = 995;
    String mailStoreType = "pop3";
    String host = "pop.i.ua
    String username = "****@i.ua
    String password = "******";

    String textPr;

    Properties props = new Properties();
    props.put("mail.smtp.port", smtpPort);
    props.put("mail.user", username);
    props.put("mail.host", host);
    props.put("mail.debug", "false");
    props.put("mail.store.protocol", "pop3");
    props.put("mail.transport.protocol", "smtp");

    Session session = Session.getDefaultInstance(props);

    Store store = session.getStore(mailStoreType);
    store.connect(host, username, password);

    Folder folder = store.getFolder("INBOX");
    folder.open(Folder.READ_WRITE);


    Message message[] = folder.getMessages();
    TextView seeMail = (TextView) findViewById(R.id.text_mail);

    for (int i = 0, n = message.length; i < n; i++) {
        String subject = message[i].getSubject();
        String sender1 = message[i].getFrom()[0].toString();
        String text = message[i].getContent().toString();
        // Date date = message[i].getReceivedDate();

        String[] parts = sender1.split(" ");
        String sender = parts[1];

        String[] parts2 = text.split("x");
        String text1 = parts2[0];

        if(i>0) {
            String mesMail = "n---------------------------------";
            mesMail += "nEmail Number " + (i + 1);
            mesMail += "nSubject: " + subject;
            mesMail += "nFrom: " + sender;
            if (text1.equals("java")) {
                textPr = "-";
            } else {
                textPr = text;
            }
            if (textPr.length() > 200) {
                textPr = textPr.substring(0, 200);
            }
            mesMail += "nText: " + textPr;
            seeMail.setText(mesMail);
        } else {
            String mesMail = "No letter";
            seeMail.setText(mesMail);
        }

    }
    folder.close(false);
    store.close();
    System.exit(0);
}