It looks like that the affected domain names have not been updated to the (new) MX hosts:
mx01.mailsecurity.swisscom.com. mx02.mailsecurity.swisscom.com.
So, I guess its a domain owner problem and not a Swisscom problem.
For example, spital-lachen.ch used to have mtainXX.mailsecurity.swisscom.com. until June 2019 and has since moved to mxXX.mailsecurity.swisscom.com.
Daniel
On 07.02.20 10:45, Tobi wrote:
Hi
hope someone from Swisscom reads here. We're currently seeing that DNS A records for MX hosts of several domains disappeared. They all using
mtainXX.mailsecurity.swisscom.com
as MX record. But there are no A records for those MX
; <<>> DiG 9.11.14-RedHat-9.11.14-2.fc31 <<>> mtain01.mailsecurity.swisscom.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 47048 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;mtain01.mailsecurity.swisscom.com. IN A
;; AUTHORITY SECTION: swisscom.com. 574 IN SOA dns3.swisscom.com. admin.dns.swisscom.com. 42532 21600 3600 604800 600
;; Query time: 0 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Fr Feb 07 10:42:03 CET 2020 ;; MSG SIZE rcvd: 113
; <<>> DiG 9.11.14-RedHat-9.11.14-2.fc31 <<>> mtain02.mailsecurity.swisscom.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 56271 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;mtain02.mailsecurity.swisscom.com. IN A
;; AUTHORITY SECTION: swisscom.com. 574 IN SOA dns3.swisscom.com. admin.dns.swisscom.com. 42532 21600 3600 604800 600
;; Query time: 0 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Fr Feb 07 10:42:03 CET 2020 ;; MSG SIZE rcvd: 113
According to our passive DNS data there are at least 63 domains using one of these hosts as their MX.
--
Cheers
tobi