@freddy servce choice is a tricky question right now and one which we carefully avoid confronting initial users with, during the default onboarding experience. Right now, we regard it as safe to use any of the listed https://chatmail.at/relays (manually curated). We are working towards "randomized" onboarding by further minimizing metadata seen by relays, and introduce multi-relay support so that choices don't easily leave you stranded in case of blocking/failure.