It is currently the situation, with Corporations Canada, that a residential address for service cannot be a postal box, except in cases where the jurisdiction is only served by a post box. That is for the purposes of protecting individuals for whom a rural route or a post box is the only means by which to address service. That is the current practice of Corporations Canada. This would actually remove the current exception, as we would see it, that allows for the post office box to serve in those jurisdictions where it is the only means by which service can be rendered.
On June 12th, 2023. See this statement in context.