spf.nic.edu.cn has no MX records.
Question and response
Question
dig spf.nic.edu.cn. MX
Answer
The response has no answer records.
Authority
nic.edu.cn. 600 SOA ns2.net.edu.cn. hostmaster.dns.edu.cn. 2024077766 7200 1800 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0