ns.checon.net has no MX records.
Question and response
Question
dig ns.checon.net. MX
Answer
The response has no answer records.
Authority
checon.net. 43200 SOA ns.checon.net. hostmaster.checon.de. 2025071101 28800 3600 864000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0