mailin.mx-hub.net has no MX records.
Question and response
Question
dig mailin.mx-hub.net. MX
Answer
The response has no answer records.
Authority
mx-hub.net. 300 SOA ns1.dnsbackup.net. root.dnsbackup.net. 2026022701 36000 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0