Use the -a option to create an anti-listing. This will ensure that no host listed in the whitelist will be blocked by rblsmtpd, even if it is listed on any other DNSBL referenced by rblsmtpd. Like this:
/usr/local/bin/rblsmtpd \
-a cabal.web-o-trust.org \
-r korea.services.net \
-r blackholes.easynet.nl \
-r opm.blitzed.org \
-r sbl.spamhaus.org \
/var/qmail/bin/qmail-smtpd 2>&1