Add reporting for mails that fail to be prepared

public interface MailListener
{
    /**
     * Called when the mail is ready to be sent but before it is actually sent.
     *
     * @param message the message to be sent
     * @param parameters some parameters specifying addition context data (for example the current wiki is stored under
     *        the {@code wiki} key)
     */
    void onPrepare(MimeMessage message, Map<String, Object> parameters);

    /**
     * Called when the mail has been sent successfully.
     *
     * @param message the message sent
     * @param parameters some parameters specifying addition context data (for example the current wiki is stored under
     *        the {@code wiki} key)
     */
    void onSuccess(MimeMessage message, Map<String, Object> parameters);

    /**
     * Called when the mail has failed to be sent.
     *
     * @param message the message that was tried to be sent
     * @param e the exception explaining why the message couldn't be sent
     * @param parameters some parameters specifying addition context data (for example the current wiki is stored under
     *        the {@code wiki} key)
     */
    void onError(MimeMessage message, Exception e, Map<String, Object> parameters);

public interface MailListener
{
    void onPrepareSuccess(MimeMessage message, Map<String, Object> parameters);
    void onPrepareError(Exception e, Map<String, Object> parameters);
    void onSendSuccess(MimeMessage message, Map<String, Object> parameters);
    void onSendError(MimeMessage message, Exception e, Map<String, Object> parameters);
}

public interface MailPrepareListener
{
    void onSuccess(MimeMessage message, Map<String, Object> parameters);
    void onError(Exception e, Map<String, Object> parameters);
}

public interface MailSendListener
{
    void onSuccess(MimeMessage message, Map<String, Object> parameters);
    void onError(MimeMessage message, Exception e, Map<String, Object> parameters);
}