The public DNSBL services offered by AHBL have been shutdown.
Services and programs which used dnsbl.ahbl.org, ircbl.ahbl.org and rhsbl.ahbl.org need to be updated in order to avoid false positives:
X-Spam-Status: No, score=0.789 tagged_above=-999 required=6
tests=[BAYES_00=-1.9, DNS_FROM_AHBL_RHSBL=2.699,
T_RP_MATCHES_RCVD=-0.01] autolearn=no
Spamassassin configuration, for example, needs to be fixed:
# cat /usr/share/spamassassin/20_dnsbl_tests.cf | grep AHBL
header DNS_FROM_AHBL_RHSBL eval:check_rbl_envfrom('ahbl', 'rhsbl.ahbl.org.')
describe DNS_FROM_AHBL_RHSBL Envelope sender listed in dnsbl.ahbl.org
tflags DNS_FROM_AHBL_RHSBL net
reuse DNS_FROM_AHBL_RHSBL
Comment that block or (at least) force a score zero for the rule in your local configuration:
# cat /etc/spamassassin/local.cf | grep AHBL
score DNS_FROM_AHBL_RHSBL 0