[exim] Restricting access to an address/alias

Hi,

We've got a general mailing alias for our entire staff, but it's
being abused as a general circulation address, rather than for
important notifications. Is there an easy way of setting a list of
'authorized users' that may mail this address, and that others get
a rejection message? Thanks.

-- 
Illtud Daniel                                 illtud.daniel@???
Uwch Ddadansoddwr Systemau                       Senior Systems Analyst
Llyfrgell Genedlaethol Cymru                  National Library of Wales
Yn siarad drosof fy hun, nid LlGC   -  Speaking personally, not for NLW