RE: https://nerdculture.de/@anon_4601/116131664815678835

Well, there's XMPP - it's federated, nowadays all server and clients are e2ee by default, it has less metadata issues than Matrix because it just passes messages, like mail does (Matrix behaves like a network-replicated database)

@lafleur
Thank you! I agree with your opinion on XMPP vs Matrix.
The problem for me is not technical but legal: the XSF (which manages the protocol) is based in Denver, USA.
With the list, we are trying to create an ecosystem completely detached from American jurisdiction for reasons of European digital sovereignty, so XMPP does not meet the criteria.
Even though it is an excellent protocol, with immense regret we have to say no.
@anon_4601 I actually was thinking about rebranding a secure subset of XMPP as eg SMPP, that would be backwards-compatible with XMPP servers implementing the needed secure parts. So to me the nationality of the rights holder is irrelevant, given the open nature of the licensing.
@anon_4601 besides, there are plenty of servers open to registration in EU, so in practice our data does never leave the continent. So as an europeaner, I upvote it again - I think promoting it is still in Europe's best interests.