mail03.theclustercompany.de has no MX records.
Question and response
Question
dig mail03.theclustercompany.de. MX
Answer
The response has no answer records.
Authority
theclustercompany.de. 3600 SOA angus.ns.servercow.de. hostmaster.servercow.de. 2026030501 14400 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0