Practically no one knows that you can email text messages, could someone abuse the crap out of it? Yes, they could... but no worse than someone can send a IM message to 123-456-1234, I know once I sent someone like 7 thousand text messages over the course of 5 or so minutes, thankfully this was before phone companies were assholes, they forgave him for the entire bill (well, beyond his normal bill)