mail.a3bc.nl has no CNAME records.
Question and response
Question
dig mail.a3bc.nl. NS
Answer
The response has no answer records.
Authority
a3bc.nl. 4961 SOA ns1.a3bc.nl. hostmaster.a3bc.nl. 2024082800 3600 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0