mxfilter1.iag.eu has no CNAME records.
Question and response
Question
dig mxfilter1.iag.eu. NS
Answer
The response has no answer records.
Authority
iag.eu. 5363 SOA a.inet.ns01.eu. do-not-reply.ivs.de. 2026011314 43200 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0