Feature request: Executables/pipes as transports, BSMTP?

[Mihara]

At least I think this is a feature request, the documentation is not very clear...

Assume I'm using NNCP which is a poorly documented but powerful way to set up highly encrypted friend-to-friend delay tolerant networks, named after UUCP and mimicking it in functionality in several respects. One of its intended uses is serving as an email transport, so one can package email for delivery and pass it through NNCP to where it needs to go.

The way to do that with Postfix and Exim is known. The only kind of transports mox appears to support are SMTP to a specific host ("smarthost"), a SOCKS proxy, and direct connection. At least, nothing else is obviously described and I don't see anything else with a quick skim through the source.

There is no way to imitate the Postfix or Exim setup described above that I can see.

1. Is this reasonably practical to implement at all, with the way mox's security works? I remember the fairly arcane (for me) systemd settings basically jailing the server process, so I wouldn't be too surprised if it's not feasible.
2. Perhaps there's a separate "buffer" localhost-smtp solution somewhere, that mox could communicate with that wouldn't be restricted from running arbitrarily chosen executables? E.g. I run something very simple on a separate port that only listens to mox, mox uses it as a transport, it does the back and forth with NNCP?