[Exim] recipients_reject_except_senders

Unfortunately in this little ORBS/MAPS war
ORBS lists an IP we want to receive mail from.
So I tried to override the ORBS reject like this:

rbl_domains =
rbl.maps.vix.com/reject:dul.maps.vix.com/reject:relays.orbs.org/reject
recipients_reject_except_senders = 204.152.186.51/32

But still the mails get blocked. Shouldn't it work
this way?
--
Torsten