[exim] blocking on rcp phase a message from/to a certain dom…

is there a way to give a 550 error to message that have as sender or
recipient any user on @unwanted.doma.in ???
(since unwanted.doma.in is a cname for the server, used only far a
particular service only from certain hosts, definively not for e-mail - it refuse
with a "lowest mx point to local host" but only after data, bouncing back ... i
wish it just drop connection immediately.


--
Leonardo Boselli
Nucleo informatico e Telematico
Dipartimento Ingegneria Civile e Ambientale
Universita` di Firenze
Via Santa Marta 3
I-50139 Firenze
+39 055-4796-431
+39 348-8605-348
fax 055-495-333