[Exim] how to duplicate sending messages

hello list,

my problem: I want to duplicate
all messages sent from the sender tom@??? to
any recipient automagically send to tom@???
How can this easily be done ?
(i.e. how can I add an second recipient when sending
with $sender_address=tom@???)

thanks for any help in advance

thomas.

--
Thomas Baumann // tirili+list.exim@???