I am travelling to AMS today on a ticket on Jet paper that involved a stop in YYZ as my first leg was on AC (though I'm not sure why it wasn't DL since they're JV partners). Even though my bag was tagged through, I had to clear Canada customs, claim my bag, take a train to Terminal 3, and re-check with Jet.

Does anyone know how YYZ does not have an airside terminal transfer and requires a luggage reclaim even for an interlined bag? I don't mind clearing customs, but it was all a pain and having to re-clear security was annoying.