I feel like Matrix may be the way forward; it also looks like it's possible to build an email-like interface on top of it. But currently, federated Matrix leaks metadata, so that's a problem.
Agree about Matrix. You get addresses such as @username:example.com , which work somewhat like email addresses. The example.com part is the homeserver, analogous to gmail.com or yahoo.com in emails. Users can communicate across homeservers.
It's also fast to setup. Took me about 30 minutes to set up a homeserver and host a customized riot client to use it.
It's not completely decentralized yet, and you can only use from a fixed list of identity servers. Although you can set up your own synapse node, you can't yet use it along with the centralized identity servers.
The reason they give for not decentralizing the identity servers yet is to avoid spam. But they plan to make them decentralized in the future, so at that point it would completely be like email.
Just to clarify: identity servers are strictly optional and are used just for mapping 3rd party IDs (3PIDs) such as phone numbers and email addresses to matrix IDs so you can be discovered or discover other users by 3PID.
They are only centralised atm because we haven't really started to attack the problem of decentralising them. What we really need is a decentralised equivalent of Keybase, but nobody has really built a suitable one yet. Blockstack is close, as are a few others, but we'd rather wait until we found something which nailed the problem and stuck with the jury-rig until then. I spoke about this at FOSDEM the other weekend: https://fosdem.org/2017/schedule/event/matrix_future/
There's also renewed community interest in fixing this over the last few days: #matrix-identity:matrix.org is a thing.
I would argue that Matrix itself is fully decentralised; it's just that some of the solutions to the optional identity discovery problem happen to be centralised. Just as some folks publish their Matrix E2E pubkeys on keybase etc.
In terms of Matrix revealing metadata: yes, it does so to the servers participating in the convo. This is really not very unusual; the problem of protecting metadata for realtime comms is very much still an open area of research (see Alpenhorn etc from CSAIL)! Hopefully it's not really a reason to turn anyone off Matrix though. I also briefly spoke about this at FOSDEM: https://fosdem.org/2017/schedule/event/encrypting_matrix/
Re: metadata: I really like Riot/Matrix and have convinced a bunch of formerly non-IRC people to start using IRC through Matrix (the great free IRC bouncer in the sky!). However, a couple of things that bother me:
- The fact that it appears to be impossible to disable typing notifications ("X is typing...") and read receipts. This can change the nature of a conversation and really should be optional. Coming from IRC, it just feels plain creepy. A friend flat-out refused to use Riot because of this.
- The fact that device information is leaked to everyone who happens to be in the same channel. So I can join #matrix and click on any of the >5k users and see information about all the devices a particular user has used. Here's from one random person: "https://riot.im/app/ via Chrome on Mac OS", "https://riot.im/app/ via Chrome on Windows", E5823 (ah, J. Doe is using a Sony Xperia Z5 Compact!), etc. Sometimes things like "Joe's iPhone" is exposed -- and I don't think Joe had any idea of that. This is bad.
