This is probably the worst part about any kind of payment based system, whether it be money or proof of work- these systems do reflect the disadvantages of the

This is probably the worst part about any kind of payment based system, whether it be money or proof of work- these systems do reflect the disadvantages of the economies of the world. That said, since this problem already exists in the world, it is often overstated. If a stamp is a reasonable cost, and only a one time cost, it will be largely invisible. 25 cents (a price set by the recipient) to send a message from a stranger won't have a big impact on most people, and it's important to recognize it's only the first time. It's further important to know it would even be possible to refund the cost of the stamp back to the sender once the message is sent. The recipient could have a button that says "Return stamp" which would then let the sender re-use or in some other way organize the stamp. Now let's contrast to today... Let's say I want to send a message to a big movie star or a CEO. The chances that I will be able to get their address is relatively low. Even if I do, they likely have someone they pay to filter their messages before it gets to them.