Domiciliation or P.O. box: what's the difference for a business in Quebec?

A domiciliation service gives you a real civic address accepted by the REQ, whereas a P.O. box only receives mail and is refused as a registered office. With a Canada Post P.O. box, nobody signs for a bailiff, nobody opens an urgent Revenu Québec notice, and nothing gets scanned. With Ancre, every envelope is photographed and read the same day, parcels from every carrier are accepted, and proof of address can be generated for the bank. The P.O. box is cheaper, but it fulfills none of the legal functions of a registered office.