[kristov]

It costs more or less the same amount of money to send one email as it does to send hundreds of thousands of emails. So spammers send hundreds of thousands of emails and they only need to fool one person to make it worthwhile financially. Is anyone doing work around "proof of work" email sending? Could a blockchain be used to make the cost of bulk email sending proportional to the volume?

[sushibowl]

The "chain" element is completely unnecessary here, since emails do not need to be strictly ordered (as opposed to currency transactions, where order is crucial). So all you need is to consider each e-mail like a standalone block and apply a proof of work to it.

This is not new, by the way. Preventing spam was the original application for PoW way before the blockchain existed. First proposed in 1997 with https://en.wikipedia.org/wiki/Hashcash

The downside is that it can be tricky to correctly tune the difficulty factor for a wide variety of e-mail sending hardware with wildly varying computing power available.

[webdelv]

http://www.hashcash.org/

[hardwaresofton]

This is a awesome idea kernel.

Somewhat related:

https://news.ycombinator.com/item?id=32340305

https://github.com/mCaptcha/mCaptcha

[p49k]

The original/first proof of work proposal, Hashcash, was in fact designed to solve email spam. It obviously served as the inspiration for Bitcoin’s proof of work component.