mail.teisa.com.py has no CNAME records.
Question and response
Question
dig mail.teisa.com.py. NS
Answer
The response has no answer records.
Authority
teisa.com.py. 9807 SOA ns1.teisa.com.py. cpanel.teisa.com.py. 2026021700 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0