Whitelist rule for reject_rbl_client in Postfix?
Solution 1:
Use check_client_access. Insert it before reject_rbl_client:
smtpd_client_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
check_client_access hash:/etc/postfix/rbl_override,
reject_rbl_client zen.spamhaus.org,
permit
Add in /etc/postfix/rbl_override
your.dynamic.dns OK
Don't forget to run postmap /etc/postfix/rbl_override
Detailed info: http://www.howtoforge.com/how-to-whitelist-hosts-ip-addresses-in-postfix