alt Hacker NewsExactly this. Spammers have the technical competence to overcome any technical hurdle, so using evidence of technical competence achieves nothing.
If it were possible to charge $0.25/email for delivery, I'd be more than happy . However, I'm sure large tech firms will need to say that is "too hard to implement at scale".
Stamp costs don't stop snail mail spam, either, unfortunately. I would be concerned if we added something like bitcoin fees to email delivery rather than curtail spam it would just further encourage grifters seeking ROI on their spam deliveries.