What a strange question. Email is decentralized, has opt-in encryption, and is usable by anyone with access to the Internet. It might be frustrating to receive

What a strange question. Email is decentralized, has opt-in encryption, and is usable by anyone with access to the Internet. It might be frustrating to receive a lot of it, but I don't know what 90% of the people who use email would want to "improve". It seems to be a fairly solved problem as a protocol - the improvements are probably just to whatever client you use to access it.