Thank you, Lena. I don't think I have looked that far down the subscription page since I set up the group. I haven't tested yet but have changed from the default setting "Subscribers only" to all email.
I am bothered that the reply has gone into a black hole. Neither sender nor owner gets any indication of that. And the settings are about emails being delivered to the owner and silent about there being no archive of them. I'll bet they are still in the system, just inaccessible from the owner's interface.