Using a PO box as a delivery address is possible, but only when you choose a Canada Post shipping method. As a rule of thumb; a postal company (in this case Canada Post) generally shouldn't have any problem with delivering to PO box addresses, although in our experience deliveries to physical addresses have a slightly higher success rate.
Local post office
It depends; even though a signature isn't required upon delivery, couriers are still obligated to make a personal drop off. This means that if nobody is available at the delivery address to accept the parcel, a courier will have to take the parcel back with him. Then, your parcel will be brought to a local pickup point (which could be a post office) for you to collect and the courier will leave a card in your mailbox to inform you of this. Please be aware that if the parcel isn't collected within 5 business days, it will be returned to sender.
If you'd like to know if it's possible to simply fill in your local post office as the delivery address, please discuss this with your local post office.
OppoSuits is not affilitated with any network of standard pickup points.