mx.webmo.fr has no CNAME records.
Question and response
Question
dig mx.webmo.fr. NS
Answer
The response has no answer records.
Authority
webmo.fr. 1795 SOA ns.phpnet.org. grenoble.phpnet.org. 2026030538 3600 1800 1209600 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0