I couldn't think of a use case for something this. For anyone else like me, the readme outlines one near the bottom which seems genuinely nice:
Set this up, allow no-auth sending from any address on your LAN, and then spinning up new local services that need outgoing mail is easy, because you can just give them the IP of the relay and omit credentials.
Set this up, allow no-auth sending from any address on your LAN, and then spinning up new local services that need outgoing mail is easy, because you can just give them the IP of the relay and omit credentials.