mail.contisystems.pt has no CNAME records.
Question and response
Question
dig mail.contisystems.pt. NS
Answer
The response has no answer records.
Authority
contisystems.pt. 300 SOA dns18.ovh.net. tech.ovh.net. 2026022600 86400 3600 3600000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0