public class Inbox {

    public static final String INBOX = "INBOX";
    public static final String POP3 = "pop3";
    public Message[] inboxMessages;

    public Inbox(final MailAdress mailAdress) throws Exception {
        Folder folder = openInboxFolder(mailAdress);
        inboxMessages = folder.getMessages();
    }

    private Folder openInboxFolder(final MailAdress mailAdress) {
        try {
            Store store = getMailStore(mailAdress);
            return inboxFolderFrom(store);
        } catch (Exception ex) {
            throw new RuntimeException("java mail error, ", ex);
        }
    }

    private Folder inboxFolderFrom(Store store) throws MessagingException {
        Folder folder = store.getFolder(INBOX);
        folder.open(Folder.READ_WRITE);
        return folder;
    }

    private Store getMailStore(final MailAdress mailAdress) throws MessagingException, NoSuchProviderException {
        Session session = Session.getDefaultInstance(new Properties());
        Store store = session.getStore(POP3);
        store.connect(mailAdress.domainPart(), mailAdress.localPart(), "");
        return store;
    }

    boolean haveMeesageWithSubject(String expectedSubject) {
        for (Message message : inboxMessages) {
            if (subjectOf(message).equals(expectedSubject)) {
                return true;
            }
        }
        return false;
    }

    private Object subjectOf(Message message) {
        try {
            return message.getSubject();
        } catch (MessagingException ex) {
            throw new RuntimeException("error reading subject", ex);
        }
    }

    @Override
    public String toString() {
        StringBuilder stringInbox = new StringBuilder();
        stringInbox.append("Mails in inbox: " + inboxMessages.length + " ");
        for (Message message : inboxMessages) {
            try {
                stringInbox.append(" [subject: " + message.getSubject() + "] ");
            } catch (MessagingException ex) {
                stringInbox.append(" [error reading message: " + ex.getMessage() + "] ");
            }
        }
        return stringInbox.toString();
    }

}