I seem to remember someone mentioning the idea that in the future you could "layer" sandstorm's grains such that you had one that was your inbox (running, say,

I seem to remember someone mentioning the idea that in the future you could "layer" sandstorm's grains such that you had one that was your inbox (running, say, Mailpile) and have a pass-through SMTP grain that was responsible solely for pgp-signing messages. That way you keep your pgp keys safe from any security vulnerabilities in your mail client. I could be misremembering, but it sounded like a cool idea.