tz.inet.co.th has no MX records.
Question and response
Question
dig tz.inet.co.th. MX
Answer
The response has no answer records.
Authority
tz.inet.co.th. 300 SOA ns2.inet.co.th. hostmaster.inet.co.th. 1417727977 28800 3600 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0