mx2.sg.aliyun.com has no TXT records.
Question and response
Question
dig mx2.sg.aliyun.com. TXT
Answer
The response has no answer records.
Authority
aliyun.com. 600 SOA hidden-master.aliyun.com. hostmaster.alibaba-inc.com. 2014073085 3600 900 1209600 600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0