I actually like this idea, and I wonder how low the cost could be while still deterring the spammers. From what I've read, the cost of domains is a factor that

I actually like this idea, and I wonder how low the cost could be while still deterring the spammers. From what I've read, the cost of domains is a factor that spammers are sensitive to, especially if they are abandoning them after 24 hours, so increasing the cost by just an order of magnitude could be enough to make many campaigns unprofitable. This article somewhat supports my assertion: https://krebsonsecurity.com/2018/06/bad-men-at-work-please-dont-click/ https://krebsonsecurity.com/2018/06/bad-men-at-work-please-d... saying "domains in the remaining five [out of ten] Top Bad TLDs can be had for between 48 cents and a dollar each." so I would suggest a one-off $100 fee rather than $500 or $1000 a year. A more interesting approach would be to make the fee act as a bond, which is returned to the registrant after a year of good behaviour. Unfortunately, determining "good behaviour" is almost as hard as determining "bad behaviour", but perhaps a domain could opt in to having anonymous metrics recorded of how many users visit their site or send emails to that domain. That would put a substantial amount of trust into the hands of whichever organisations were responsible for recording these metrics, but the only harm they could do to a registrant is forcing them to pay their $100 bond to charity.