Joined Cases C-434/19 and C-435/19: Judgment of the Court (Fifth Chamber) of 3 March 2021 (requests for a preliminary ruling from the Corte suprema di cassazione — Italy) — Poste Italiane SpA (C-434/19), Agenzia delle entrate — Riscossione (C-435/19) v Riscossione Sicilia SpA agente riscossione per la provincia di Palermo e delle altre provincie siciliane (C-434/19), Poste Italiane SpA (C-435/19) (References for a preliminary ruling — State aid — Competition — Article 107(1) TFEU — Conditions under which applicable — Article 106(2) TFEU — Services of general economic interest — Management of the post-office account used for collection of the municipal real estate tax — Undertakings benefiting from special or exclusive rights granted by the Member States — Fees set unilaterally by the recipient undertaking — Abuse of dominant position — Article 102 TFEU — Inadmissibility)