I have been looking into this type of system with a colleague for a few years now. We have been working on a concept of an attention based email network which i

I have been looking into this type of system with a colleague for a few years now. We have been working on a concept of an attention based email network which is essentially a way to map our natural limited attention to the digital world. This type of system requires a mindset that involves multiple parties, not just the receiver, so it becomes a non-trival exercise when considering the attention of multiple parties using multiple email systems. In a practical sense, we looked at adding a multi party reputation system to the email standard which would involve adding meta data to emails to indicate the "trust" level between the recipients. There are clearly quite a number of technical challenges for this type of system. Fastmail seems to be doing some interesting work in this space. https://fastmail.blog/2015/12/17/the-endless-battle-against-spam/ https://fastmail.blog/2015/12/17/the-endless-battle-against-... https://tools.ietf.org/html/rfc5322#section-2.1.1 https://tools.ietf.org/html/rfc5322#section-2.1.1