sm1.cet.com has no MX records.
Question and response
Question
dig sm1.cet.com. MX
Answer
The response has no answer records.
Authority
cet.com. 38400 SOA ns0.cet.com. hostmaster.cet.com. 2025060202 10800 3600 604800 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0