m5689.contaboserver.net has no MX records.
Question and response
Question
dig m5689.contaboserver.net. MX
Answer
The response has no answer records.
Authority
contaboserver.net. 3600 SOA ns1.contabo.net. hostmaster.contabo.de. 1772710863 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0