Canadian here, I have received these letters in the past through my ISP, once for a dl I did (yeah I raw dogged it), and 1 or 2 from the kid that lives in my house. ISP says basically "We got this letter, we need to forward it to you, we have passed on no information to the sender. Please don't get caught doing this again. Thank you". Not sure what would happen if there were hundreds of files downloaded but my ISP is a pretty good one for doing the bare legal minimum to correct users.