smtp.dsm.gmessaging.net has no MX records.
Question and response
Question
dig smtp.dsm.gmessaging.net. MX
Answer
The response has no answer records.
Authority
dsm.gmessaging.net. 300 SOA ns6.oleane.net. root.dsm.gmessaging.net. 2018100245 1200 300 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0