I beleive that e-mail system was designed without much security concerns because it was not a problem then, many years ago.
I just think secure mailing systems will come into life and spammers will not exist.

It is not CPU cycles that spammers fight against anti-spammers, but rather design problem: I have no spam on my HDD just because I have enough policies to not allow anyone to go there.

Best regards,
Courage, the Cowardly Dog