The thing about RiseUp is that any system containing the email accounts of a significant number of activists is bound to become a target. This is why if you want better security it's a good idea to run your own stuff, or get someone you trust to do that. #Freedombone now includes Mailpile, which makes encrypted email quite easy although has the down side that it doesn't handle multiple users on one server.
https://gnusocial.freedombone.net/url/2099