ns2.kundencontroller.de has no MX records.
Question and response
Question
dig ns2.kundencontroller.de. MX
Answer
The response has no answer records.
Authority
kundencontroller.de. 500 SOA k1.kundencontroller.de. root.k1.kundencontroller.de. 2008012102 28800 7200 604800 500
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0