The fact that the service exists is evidence of the problem.
Canada's anti spam law just went into effect for email, companies can't (see arent supposed to) just email you out of the blue anymore, why can't this apply to snail mail as well?
I think the answer is because the postal service survives on the revenue they get from stuffing your mail box with garbage, but I assert that's not a good enough reason. If they can't keep themselves afloat without the spam. I question whether they need to exist at all in the age of free webmail accounts and the ability to run your own server.