ns1.itmuller.com has no MX records.
Question and response
Question
dig ns1.itmuller.com. MX
Answer
The response has no answer records.
Authority
itmuller.com. 60 SOA ns1.nodesecure.com. support.itmuller.com. 2025033731 43200 7200 1209600 60
Additional
. 0 OPT ; payload 1400, xrcode 0, version 0, flags 0