I am using zen.spamhaus.org but I noticed this in the logs.
May 7 02:33:58 web1 spamd[9609]: dns: sendto() failed: Connection refused at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/DnsResolver.pm line 340, line 53.
May 7 02:33:58 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 53.
May 7 02:49:22 web1 spamd[9609]: dns: sendto() failed: Connection refused at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/DnsResolver.pm line 340, line 144.
May 7 02:49:23 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 144.
May 7 02:49:23 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 144.
May 7 02:49:37 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 144.
May 7 02:49:39 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 144.
May 7 02:49:39 web1 spamd[9609]: spamd: identified spam (9.2/5.0) for tek7.cgalliance:502 in 19.8 seconds, 6583 bytes.
May 7 02:49:39 web1 spamd[9609]: spamd: result: Y 9 - EXTRA_MPART_TYPE,HTML_IMAGE_ONLY_12,HTML_MESSAGE,HTML_SHORT_LINK_IMG_1,PART_CID_STOCK,PART_CID_STOCK_LESS,STOCK_IMG_HDR_FROM,STOCK_IMG_HTML,TVD_FW_GRAPHIC_ID1,WHY_WAIT scantime=19.8,size=6583,user=tek7.cgalliance,uid=502,required_score=5.0,rhost=localhost.localdomain,raddr=127.0.0.1,rport=38941,mid=<000801c8b027$03b2d1f4$938dae81@pnxmtli>,autolearn=no
May 7 03:09:19 web1 spamd[9609]: dns: sendto() failed: Connection refused at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/DnsResolver.pm line 340, line 27.
May 7 03:09:19 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 27.
May 7 03:22:32 web1 spamd[9609]: dns: sendto() failed: Connection refused at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/DnsResolver.pm line 340, line 91.
May 7 04:07:43 web1 spamd[9609]: dns: sendto() failed: Connection refused at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/DnsResolver.pm line 340, line 86.
May 7 04:07:43 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 86.
May 7 04:07:43 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 86.
May 7 04:07:58 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 86.
May 7 04:08:00 web1 spamd[9609]: Use of uninitialized value in exists at /usr/lib/perl5/vendor_perl/5.8.8/Mail/SpamAssassin/Plugin/URIDNSBL.pm line 701, line 86.
It goes on and on at different lines.