The parent comment isn't talking about proof of work it's talking about actual payment. In practice payment system are much more rarely compromised (or at least it doesn't last long) and if you could compromise someone's payment system you'd not bother sending spam, you'd just take the money and run.
>The parent comment isn't talking about proof of work it's talking about actual payment.
I think he was replying to this that the gp wrote: "The best part of this system is that it really does not require actual money [...] , he could just _mine_ the coins he uses to send the mail with."
