smtpfilter.pr.gov.br has no CNAME records.
Question and response
Question
dig smtpfilter.pr.gov.br. NS
Answer
The response has no answer records.
Authority
pr.gov.br. 4991 SOA pr.gov.br. root.pr.gov.br. 2026030204 1800 300 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0