[Exim] Hosts notations in relay hosts...

I read the specs and tried:

hostlist   relay_from_hosts = x.x.0.0/20 \
                                :127.0.0.1

but people on x.x.176.y net (and the others on the /20 subnet) can't
relay email without authentication. I have to put every IP in the subnet
on the list?

[]s
core