smtpsys01nec.opaltelecom.net has no MX records.
Question and response
Question
dig smtpsys01nec.opaltelecom.net. MX
Answer
The response has no answer records.
Authority
opaltelecom.net. 300 SOA ds0.opaltelecom.net. noc.opaltelecom.net. 2026022400 600 7200 2592000 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0