relay.uhp-cesson.gmessaging.net has no MX records.
Question and response
Question
dig relay.uhp-cesson.gmessaging.net. MX
Answer
The response has no answer records.
Authority
uhp-cesson.gmessaging.net. 3600 SOA ns6.oleane.net. helpdesk.atlas.fr. 2019012314 1200 300 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0