Kernrechtsfrage
Whether the payment reminder under Art. 257d OR was invalid because one signatory lacked authority and later ratification came too late.
Extrahierter Entscheid
The reminder was valid: post hoc ratification by the landlord cured the missing authority, and the cure related back to the time of the act.
Extrahierte Begründung
Agency rules apply beyond contract formation to other legally relevant acts. A ratification can validate an unauthorized notice, and no factual finding showed any relevant uncertainty for the tenants before ratification.