Charles Lindsey wrote:
Which is why I said "The only place where it *can* be known ...". For
sure, if the author does not know, then there is even less chance that
subsequent mailing list expanders would know
Amazing -- this has been explained to you in detail several times
and you still don't get it! One last time:
Author A sends a message to mailbox foo. That mailbox, unbeknownst
to A, is a mailing list mailbox, which is expanded to multiple
addresses (any one of which might be yet another mailing list
mailbox). Although A knows nothing about any of those lists,
clearly the administrator of the list associated with mailbox foo
knows that it expands to a mailing list, as do any administrators
of any such downstream lists.