sg-1-0.ptr.blmpb.com has no MX records.
Question and response
Question
dig sg-1-0.ptr.blmpb.com. MX
Answer
The response has no answer records.
Authority
blmpb.com. 300 SOA ns1.volc-dns.com. dnsadmin.bytedance.com. 2023051515 3600 1200 86400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0