This means that Customs intends to carry out an inspection prior to departure. Customs will normally contact you within two hours. If this is not the case, you can inquire with the office of departure, NL000510. You can do so by calling +31 181 373 737 with the question whether the inspection still needs to be performed or, if not, whether permission to depart can be granted.
You can change your permissions via 'customise preferences'.