] Comcast, the country's largest provider of high-speed
] Internet access, has begun blocking a channel frequently
] exploited by spammers to send out large volumes of
] e-mail, a move that many technologists say was long
] overdue and should be matched by other service providers.

I think maybe the right answer here is to firewall port 25 by
default and turn it back on for people who know what they're doing.

Comcast to Firewall Port 25