PTR does not work

Hello, today I noticed, that no tunnel IP has a working PTR record. A few days ago the resolving of IPv6 adresses into hostnames must have worked, because I'm running a mailserver on one IP of the tunnel subnet and the only mailserver I currently reach via IPv6 is bouncing messages when no PTR is present. First, I checked both of my authorative DNS servers, but they're working properly. Heres the result of a "dig" on one tunnel IP, but it's represantative for other IPs: <code> rejectix:~# dig -x 2a01:198:490::e +trace ; <<>> DiG 9.5.1-P3 <<>> -x 2a01:198:490::e +trace ;; global options: printcmd . 84163 IN NS j.root-servers.net. . 84163 IN NS f.root-servers.net. . 84163 IN NS b.root-servers.net. . 84163 IN NS k.root-servers.net. . 84163 IN NS a.root-servers.net. . 84163 IN NS e.root-servers.net. . 84163 IN NS c.root-servers.net. . 84163 IN NS m.root-servers.net. . 84163 IN NS l.root-servers.net. . 84163 IN NS g.root-servers.net. . 84163 IN NS d.root-servers.net. . 84163 IN NS i.root-servers.net. . 84163 IN NS h.root-servers.net. ;; Received 509 bytes from 78.46.93.84#53(78.46.93.84) in 35 ms ip6.arpa. 172800 IN NS ns.icann.org. ip6.arpa. 172800 IN NS ns2.lacnic.net. ip6.arpa. 172800 IN NS sec1.apnic.net. ip6.arpa. 172800 IN NS ns-sec.ripe.net. ip6.arpa. 172800 IN NS tinnie.arin.net. ;; Received 229 bytes from 2001:500:3::42#53(l.root-servers.net) in 162 ms 0.a.2.ip6.arpa. 84600 IN NS ns2.lacnic.net. 0.a.2.ip6.arpa. 84600 IN NS ns-pri.ripe.net. 0.a.2.ip6.arpa. 84600 IN NS tinnie.arin.net. 0.a.2.ip6.arpa. 84600 IN NS sec3.apnic.net. 0.a.2.ip6.arpa. 84600 IN NS sec1.apnic.net. ;; Received 302 bytes from 2001:610:240:0:53::4#53(ns-sec.ripe.net) in 45 ms 8.9.1.0.1.0.a.2.ip6.arpa. 172800 IN NS ns1.dnspartner.de. 8.9.1.0.1.0.a.2.ip6.arpa. 172800 IN NS ns2.dnspartner.de. ;; Received 139 bytes from 2001:dc0:2001:a:4608::59#53(sec1.apnic.net) in 395 ms 8.9.1.0.1.0.a.2.ip6.arpa. 86400 IN SOA ns1.dnspartner.de. hostmaster.speedpartner.de. 2010051100 28800 7200 604800 86400 ;; Received 167 bytes from 84.19.176.110#53(ns2.dnspartner.de) in 38 ms </code> Could you check, if your PTRs are working? Or does it have something to do with the "DENIC desaster" today? Thank you for your work! Much greetings from Wuppertal, Germany