dnssec1.dotvndns.vn has no MX records.
Question and response
Question
dig dnssec1.dotvndns.vn. MX
Answer
The response has no answer records.
Authority
dotvndns.vn. 3600 SOA ns1.dotvndns.vn. hostmaster.dotvndns.vn. 2026020101 14400 3600 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0