mx.dev-my.games has no CNAME records.
Question and response
Question
dig mx.dev-my.games. NS
Answer
The response has no answer records.
Authority
dev-my.games. 212 SOA ns1.dev-my.games. telecom.dev-my.games. 2019100214 600 300 1200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0