cru.fr has no MX records.
Question and response
Question
dig cru.fr. MX
Answer
The response has no answer records.
Authority
cru.fr. 3600 SOA ns1.renater.fr. hostmaster.renater.fr. 2022012816 3600 600 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0