ns.ipn.de has no MX records.
Question and response
Question
dig ns.ipn.de. MX
Answer
The response has no answer records.
Authority
ipn.de. 43200 SOA ns.ipn.de. support.ipn-b.de. 2024091301 10800 3600 604800 43200
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0