net.orange.es has no MX records.
Question and response
Question
dig net.orange.es. MX
Answer
The response has no answer records.
Authority
net.orange.es. 172800 SOA ns1.orange.es. dnsmaster.es.orange-ftgroup.com. 498 86400 7200 2592000 172800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0