[exim] system wide message filter

Dear List members, good morning.

I am a little stuck with a strange request from my line manager, and no
amount of google search yielded any usable result. So, I would like to
request some help / pointer

I have been told that I need to set a filter so if any email, either
incoming or outgoing, internal or otherwise, contains certain particular
word that those emails will need to be sent to a pre-defined google account.

Example. If the email body contains the term "Donald Duck" or just
"duck" or "Duck" or "Donald" etc., then a copy of that email will need
to be sent to duckload@???

My understanding is, I need to set up a systemwide filter, let it do some
if $message_body matches "Duck"
then
deliver duckload@???
endif

But that is not working.

I have two-fold problem. first, I would like to set up a txt file from
which the key word(s) can be lsearch-ed, preferably with some regular
expression. second is, I don't think "deliver" is the correct option.

Any pointer/suggesion on the matter would be greatly appreciated. I have
already gone through the exim filter specification, but maybe I have
missed it, so specific pointers would be even more helpful.

Thanks and regards