vip4.alidns.com has no MX records.
Question and response
Question
dig vip4.alidns.com. MX
Answer
The response has no answer records.
Authority
alidns.com. 1200 SOA ns3.aliyun.com. hostmaster.alibabadns.com. 2018052320 3600 1200 3600 360
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0