reverse.open-telekom-cloud.com has no MX records.
Question and response
Question
dig reverse.open-telekom-cloud.com. MX
Answer
The response has no answer records.
Authority
reverse.open-telekom-cloud.com. 300 SOA ns1.open-telekom-cloud.com. dl-otc-domains.telekom.de. 1 7200 900 1209600 300
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0