mxbsg.socketlabs.com has no MX records.
Question and response
Question
dig mxbsg.socketlabs.com. MX
Answer
The response has no answer records.
Authority
socketlabs.com. 900 SOA ns-929.awsdns-52.net. dnsadmin.socketlabs.com. 2017110200 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0