Delta Chat is so very cool.
I have a security feature for the future. DeltaChat can already automatically delete messages after different periods of time on the server. That’s very cool! But it would be even cooler if DeltaChat could make a local or wherever stored backup beforehand. Then you have the messages, but the mail provider doesn’t.
You just have to set “delete messages on device” to never.
So you have your “backup”
This is already how it works, if you delete messages on the server the client keeps it. Delta Chat downloads every message at most once, after that it does not matter if it exists on the server.