Steve, it takes time (admittedly a small amount for each instance, but cumulatively...) to determine if the email is spam, and then delete it, and then block it. I only have a finite amount of time in this world, and hate to waste it on stuff like that.

The internet has incredible potential, and it gets wasted on junk mail and porn.

We need some enforcement of the laws in place: http://www.spamlaws.com/