With the client code being open source, everybody can build the client themselves, run it locally and verify that the open source code is being used. If we published the server code open source, this would not be the case: No one would be able to verify that the open source server code is actually running on our server - so publishing it is a bit pointless.- Tuta
So we continue in the reality where Tuta runs code on their sever and it is a mystery. It could be an amazing application. It could be a cellular automata that runs an email server.
I think I might start calling these organic tech. Because they take a word we know, "open source", and then use it like the food companies used "organic" stickers.