ns2.open-telekom-cloud.com has no MX records.
Question and response
Question
dig ns2.open-telekom-cloud.com. MX
Answer
The response has no answer records.
Authority
open-telekom-cloud.com. 3600 SOA ns1.open-telekom-cloud.com. dl-otc-domains.telekom.de. 2000010101 86400 600 120960 86400
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0