I recently observed a problem when a subscriber is set to repro on
a list with

* Send = public

The subscriber is a member of the list and he is registered with his
address <user@domain>. The repro option is set for this subscription. Now
this user decided to change his "From:" field and send his mail from a
slightly different address which looks like <username@domain> (which is a
valid alias for his mail account). This address is *not* subscribed to the
list. Now the local MTA (Exim) inserts a "Sender:" field

Sender: user@domain

into the header of his mail and when he sends mail to the list, his mail
is distributed to the list members but he does *not* receive a repro copy.
Is there a rule that prevents repro copies from being sent to addresses
which appear in a "Sender:" field?

Regards,

Siegfried