The bug hit the country’s 8,500 post offices on Monday morning and by mid-afternoon was still not fixed.
The firm’s tech teams were working to repair the fault, which La Poste says appears to be a technical failure and not the result of hacking.
The firm’s internet and ATM cash machines were operating normally, it said.
Sans informatique #LaPoste @lisalaposte @LaPosteBusiness ne sait pas du tout fournir un recommandé, pas de plan de secours, pas de recherche manuelle possible, mais d’informatique nulle part de la journée ?? pic.twitter.com/m8qSu49hbf
— Hervé Schauer (@Herve_Schauer) April 9, 2018