To stop rblsmtpd from now allowing users to send mail to ips that have been black listed you can chang the option that rblsmtpd is using from '-r' to '-a' in the following file:

/etc/xinetd.d/smtp_psa 

Orignal smtp_psa:

# cat /etc/xinetd.d/smtp_psa.orig

service smtp
{
        socket_type     = stream
        protocol        = tcp
        wait            = no
        disable         = no
        user            = root
        instances       = UNLIMITED
        server          = /var/qmail/bin/tcp-env
        server_args     = -Rt0 /usr/sbin/rblsmtpd  -r bl.spamcop.net -r sbl-xbl.spamhaus.org -r sbl.spamhaus.org /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true
}

New smtpd_psa:

# cat /etc/xinetd.d/smtp_psa

service smtp
{
        socket_type     = stream
        protocol        = tcp
        wait            = no
        disable         = no
        user            = root
        instances       = UNLIMITED
        server          = /var/qmail/bin/tcp-env
        server_args     = -Rt0 /usr/sbin/rblsmtpd  -a bl.spamcop.net -r sbl-xbl.spamhaus.org -r sbl.spamhaus.org /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true
}

Once the above changes have been made you will now need to restart qmail:

 # /etc/init.d/qmail restart