[Mailman-Users] Filtering Reply to list with informative rejection message

[francis picabia]

We already have settings under General for stripping the original Reply-To
and reply goes to list is set as Poster.

We have experienced a case where nominations were solicited from the list
members, and there was a response with confidential information which went
to the list rather than the poster.

There is a possibility management will want to block all replys to the
mailing list.  One could work around it by making a fresh email to the list.

The Spam Filter rule to Reject based on finding "^In-Reply-To:" works well,
but the simple rejection is not going to be understood by our users:

Message rejected by filter rule match

We can customize that in the source, but it would impact all lists.

Holding for moderation isn't an option because we have enough volume and
email outside of office hours that this wouldn't be workable.

I see a way to send a custom message to non-members of a list.  That won't
fit.

I see a way to send a custom message to moderate members, which we don't
want either.

Is there another option I have not covered or I have misunderstood
something here?