AmonRa on Nostr: As far as I know you cannot, it's not perfect, if you want a truly secure email ...

As far as I know you cannot, it's not perfect, if you want a truly secure email provider, protonmail, for example, is better, duck uses their own email infrastructure but this service is purely for forwarding purposes only, they store the forwarding address and alias (encrypted) and since they are US based I wouldn't call it secure.