The service of the notice is likely to be invalid as direct service has been arranged. The applicable European Convention on the Service of Documents in Administrative Matters of 24.11.1977 provides for direct service by the foreign authority, but Germany has expressly objected to direct service.
A decision by the Italian Supreme Court ("Corte di Cassazione") on November 3, 2020 confirmed the ineffectiveness of serving a fine notice abroad by post. The case concerned a German citizen who received a fine notice from the Florence police directly by post. According to previous case law, the objection of ineffectiveness of service had to be raised in the objection proceedings, but according to the current judgment of the Corte di Cassazione of 08.04.2022, the ineffectiveness of service is cured if the objection is lodged within the time limit. For strategic reasons, it is therefore advisable to file the objection at a later date, e.g. in the unlikely event of an enforcement attempt by the authority.