Hi. If you don't want change DNS resolver for all DNS queries from your server you can add in SA config line:
dns_server x.y.z.k:53 where z.y.z.k is IP DNS server using to resolve only by SA. Then in resolv.conf you can use different (ex. ISP) DNS server. More info: http://spamassassin.apache.org/full/3.4.x/doc/Mail_SpamAssassin_Conf.html#port Best Regards.
