spamfilter4.loading.es has no CNAME records.
Question and response
Question
dig spamfilter4.loading.es. NS
Answer
The response has no answer records.
Authority
loading.es. 2992 SOA ns1.gandi.net. hostmaster.gandi.net. 1771505826 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0