mb02.mediaber.de has no MX records.
Question and response
Question
dig mb02.mediaber.de. MX
Answer
The response has no answer records.
Authority
mediaber.de. 3600 SOA ns1.first-ns.de. dns.hetzner.com. 2022081702 14400 1800 604800 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0