rbl checks, best place

[Dave]

Hello,
        I'm running postfix, amavisd-new and spamassassin. Currently in my
postfix smtpd_recipient_restrictions right at the end last thing i have some
rbl checks. I'm wondering if that's the best place for them or should i
disable that and activate them in spamassassin? Suggestions welcome.
Thanks.
Dave.