dns4.planisys.net has no MX records.
Question and response
Question
dig dns4.planisys.net. MX
Answer
The response has no answer records.
Authority
planisys.net. 60 SOA dns1.planisys.net. admin.planisys.net. 2021084988 3600 600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0