spf.dtac.co.th has no MX records.
Question and response
Question
dig spf.dtac.co.th. MX
Answer
The response has no answer records.
Authority
dtac.co.th. 450 SOA ns5.dtac.co.th. please_set_email.absolutely.nowhere. 2022112401 1800 300 2592000 450
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0