a.dns.cn has no MX records.
Question and response
Question
dig a.dns.cn. MX
Answer
The response has no answer records.
Authority
dns.cn. 43200 SOA a.dns.cn. root.cnnic.cn. 2023110101 3600 600 1209600 43200
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0