Bruce I agree with Paul and bondposters, and can vouch for it. Hell, send an empty tube to him one day, and see.
They can and will get through that tube if they wanted to.
I had one poster from Royal Mail, (again, you can say maybe it was Canada Post), but that was the only one I seen like that, and that came from UK when I ordered it.
The Tube was EXTREMELY sturdy.It was almost 1/8", probably more thick. And somehow they got through it. Even by jumping on it, it would not budge. You needed to run over it or something to get like that. Constant dents, like one had stated, the ends were both smashed as well.
This was it from a long while ago, I always keep it on file to show how F***ed it was, and that neither post office dealt with it or gave me an explanation.