mx.agps-poitoucharentes.com has no CNAME records.
Question and response
Question
dig mx.agps-poitoucharentes.com. NS
Answer
The response has no answer records.
Authority
agps-poitoucharentes.com. 3600 SOA dns.agps-poitoucharentes.com. hostmaster.agps-poitoucharentes.com. 1742285212 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0