mail.worldstream.nl has no CNAME records.
Question and response
Question
dig mail.worldstream.nl. NS
Answer
The response has no answer records.
Authority
worldstream.nl. 8 SOA ns1.worldstream.nl. hostmaster.worldstream.nl. 2026021101 10800 3600 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0