As of January 1, the Abusive Hosts Blocking List (AHBL.org) wildcarded all zones no longer in operation, including rhsbl.ahbl.org, dnsbl.ahbl.org, and ircbl.ahbl.org.  This means that these services will return positive responses for any queries.

This causes nukeSPAM™, which uses the DNSBL, to block all registrations. To correct this, simply disable the AHBL blocking in the nukeSPAM™ DNS Blacklists configuration.