I have made the following settings for 2 servers since some months:
smtpd_client_restrictions = permit_mynetworks, permit_sasl_authenticated, permit_dnswl_client list.dnswl.org, reject_rbl_client dnsbl-1.uceprotect.net, reject_rbl_client rbl.interserver.net, reject_rbl_client bl.0spam.org...