Flat fees for certificates are much more acceptable, and would probably end up being pretty low.

But I think you’re wrong about what innovations would be stopped. I’m building code that will send email on behalf of users. It will not receive mail. If I get lots of free users sending millions of mails, how do I pay the per-email fees? More to the point, why should I even have to worry about it?

Yes, hotmail receives mail, and if you take the goodmail model they might win on the balance (not sure that’s good) but friendster and many other apps don’t receive, they just send. Anonymous remailers, so important in the history of the net, also would never have been able to exist. If the prices are enough to scare spammers, they are enough to scare any legit app that dreams of success.

Everybody underestimates how much simple permissions and costs stomp on innovation. Look at crypto export regs to learn otherwise. You just had to do paperwork to export crypto, no regs if you just went domestic — result was effectively no good crypto in software for 7 years. Apps should be judged on more than whether they are financially viable.