castle-it.net has no MX records.
Question and response
Question
dig castle-it.net. MX
Answer
The response has no answer records.
Authority
castle-it.net. 180 SOA castle-it.net. ythomas.castle-it.fr. 2020120401 3600 3600 1209600 604800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0