Interesting. I double-checked the "program rules" in the eIS Seller Terms and Conditions and I couldn't find anything that stated that sellers had to send their items to the eIS hub via a trackable shipping method.
However, your seller is unlikely to get the protections that eIS offers without evidence that the item they sent out made it to the eIS hub, so there's that.
eIS doesn't tie the shipping information to the tracking information provided by the seller, though. I'm pretty sure a reference code is added to the shipping address that eBay provides the seller, and that's what eIS uses to check in items. I don't know what happens when the eIS's tracking information tries to piggyback onto a shipment with no initial tracking recording, though.
As for your question about Canada Post, keep in mind that eIS uses other carriers besides ones that use the postal system, so there's a chance your item might be sent out by other means, but if you live in a rural or remote location that's probably not going to do you any good. At any rate, a not-received item is a not-received item, but you can't file a case for one until after the last estimated date of delivery has passed and I suspect that's still a week or so away.
