spf.vnptemail.vn has no MX records.
Question and response
Question
dig spf.vnptemail.vn. MX
Answer
The response has no answer records.
Authority
vnptemail.vn. 3600 SOA ns1.vdconline.vn. vdconline.tld. 2026021164 28800 7200 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0