smtp.coreix.net has no MX records.
Question and response
Question
dig smtp.coreix.net. MX
Answer
The response has no answer records.
Authority
coreix.net. 3600 SOA authns1.coreix.net. hostmaster.coreix.net. 2026011401 3600 900 1048576 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0