webmail.priotas.com has no CNAME records.
Question and response
Question
dig webmail.priotas.com. NS
Answer
The response has no answer records.
Authority
priotas.com. 3447 SOA rc78.3uu.net. hostmaster.3uu.net.priotas.com. 2025123111 3600 3600 3600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0