*/
    boolean isMailSendMock();

    /**
     * Get the value for the key 'mail.smtp.server.main.host.and.port'. <br>
     * The value is, e.g. localhost:25 <br>
     * comment: SMTP server settings for main: host:port
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */