I note this in the opening paragraph of
www.skally.net/listowner/email/

                                    Listserv does not seem to recognize
   Reply-To in messages, only the FROM field when determining if the
   sender is authorized to send a command or post. But it is worth trying
   to set the replyto field in email programs to see if that will make a
   difference, sometimes it seems to.


Well, it shouldn't accept Reply-to: as the equivalent of From:, the two
fields have absolutely no necessary link, logically or by the rules. Isn't
this sort of saying " From:  Sender: Reply-to:, pick the one you want to
use, doesn't matter, who cares, they all mean the same thing, don't
they?", which is what some braindead mail systems seem to do?

In instances where a potential subscriber says he repeatedly has sent a
proper SUBSCRIBE command and never gets any response at all, and the
person does it again with a cc: to me, and yep, did it all correctly, I
have sometimes found that when the person's mail is sent it does have the
From:  field which he thinks (has been told) it is, From: [log in to unmask]
BUT, study of the header shows that it is REALLY from [log in to unmask]
Some sites tell their people about this aliasing, and to put in a
Reply-to: field with the "true" address, but LISTSERV properly ignores
that for commands.  For such people one can do an ADD with the true
address (not the same as their From: field) and they will have no problem
with their sub even though it isn't the address they think it ought to be
(watch out for this if you are in the habit of using the CHANGE command
for subscriptions).

As to LISTERV knowing what Reply-to: means, well, I think it does, as
is demonstrated if you have in your list header Reply-to= Both,Respect

Douglas