spf-sg.qcloudmail.com has no MX records.
Question and response
Question
dig spf-sg.qcloudmail.com. MX
Answer
The response has no answer records.
Authority
qcloudmail.com. 180 SOA ns3.dnsv2.com. level3dnsadmin.dnspod.com. 1769756873 3600 180 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0