spamfilter.cloudlink.pt has no CNAME records.
Question and response
Question
dig spamfilter.cloudlink.pt. NS
Answer
The response has no answer records.
Authority
cloudlink.pt. 1479 SOA lara.ns.cloudflare.com. dns.cloudflare.com. 2396706886 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0