ns3.cetsi.info has no MX records.
Question and response
Question
dig ns3.cetsi.info. MX
Answer
The response has no answer records.
Authority
cetsi.info. 86400 SOA ns1.cetsi.fr. postmaster.cetsi.fr. 2014643340 21600 3600 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0