arg

I'm assuming you're being facetious, but with print mail, the vast majority of the cost is borne by the mailer...the recipient merely has to pull it out of the box and throw it away, compared to probably 20 cents for a postcard up to several dollars for a mailed catalog. That keeps it somewhat in check.

With email spam, you can send, I dunno, maybe a million messages for a hundred bucks or something? The cost and inconvenience to the million recipients, and their mail providers, substantially outweighs the spammer's cost.

The same thing happened with phone spam, as technological and infrastructure improvements drove down the cost of telemarketing (robodialers, etc.), to the point where the public finally reached their limit and we now have the federal do-not-call list.