mxb.dnsdrift.net has no MX records.
Question and response
Question
dig mxb.dnsdrift.net. MX
Answer
The response has no answer records.
Authority
dnsdrift.net. 86400 SOA ns.dnsdrift.net. registry.exeo.se. 1764064339 3600 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0