AT&T customers have contacted us saying they can't reach any of our DNSBLs, seems AT&T have defined a fake sbl.spamhaus.org zone in their DNS servers so when AT&T customers ask AT&T's NS 12.149.189.2 for sbl.spamhaus.org they get: ;; ANSWERS: sbl.spamhaus.org 86400 IN SOA loopback root.loopback ( 1 ; serial 3600 ; refresh 600 ; retry 3600000 ; expire 86400) ; minimum ;; AUTHORITY RECORDS: sbl.spamhaus.org 86400 IN NS loopback ;; ADDITIONAL RECORDS: loopback 61703 IN A 127.0.0.1 And it's not just affecting our users... blackholes.mail-abuse.org 86400 IN SOA loopback root.loopback blackholes.mail-abuse.org 86400 IN NS loopback loopback 61520 IN A 127.0.0.1 cbl.abuseat.org 86400 IN SOA loopback root.loopback cbl.abuseat.org 86400 IN NS loopback loopback 61480 IN A 127.0.0.1 list.dsbl.org 86400 IN SOA loopback root.loopback list.dsbl.org 86400 IN NS loopback loopback 60855 IN A 127.0.0.1 -- Steve Linford The Spamhaus Project http://www.spamhaus.org