demo.push.atosworldline.com has no MX records.
Question and response
Question
dig demo.push.atosworldline.com. MX
Answer
The response has no answer records.
Authority
atosworldline.com. 28800 SOA dns1.cscdns.net. hostmaster.cscdns.net. 2025032003 43200 7200 1209600 28800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0