JMAP – a modern email open standard
Sounds like the big claim here is that it is faster. That's definitely a  good thing, but what I want is a protocol where:<p>1. Every time I give out my email address, behind the scenes a single-source permission/token is created.
2. Thus, that one source is able to send me email, from the email address they specified at the time. 
3. But if they hand over the permission/token to anyone else, email from that new source will automatically bounce/be marked as suspect/flagged (my choice in configuration).
4. Even if the original authorized party tries to email me from a different address at the same domain, that email will be handled as in (3).
5. Even from the same email address, the configuration can specify limits, e.g. only 5 emails total, only 3 per week, expire after 10 days, etc. Again, configurable.<p>Oh, and 6. Of course this means unsubscription becomes a local configuration thing that doesn't require the sender's participation.<p>I know current email protocols allow none of that, but if we're proposing new protocols, that's what I want out of it. Faster is better too.