[amelius]

You mean like e-mail? Sadly, most people use gmail now and there are whitelists so you don't get to write your own email server.

[whymarrh]

Similarly, basically everyone using Ethereum just uses Infura nodes [1]. Web3 is no more decentralized than anything it purports to improve upon.

[1]: https://infura.io/

[Chris2048]

I feel email could really do with disruption.

Least of all: require escrow-held-micro-payment to send an email to some location. If the item is marked as spam, the sender loses their money (perhaps to the spam-filter maintainer).