mail.tvintel.org has no CNAME records.
Question and response
Question
dig mail.tvintel.org. NS
Answer
The response has no answer records.
Authority
tvintel.org. 10800 SOA ns1.tvintel.org. root.tvintel.org. 1197 38400 10800 259200 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0