Did you see what the Royal Mail did to a thick poster tube I received Angelo. I'm not sure what subject title it's under, but it's in the packing thread.
Yes, that poster tube was that strong I had to stand on it ( and I've put some weight on in the last few years ) and bounce up and down on it, to open it up enough so the poster would come out of the tube.
Maybe Canada post is to blame after they took over?