mail.teiath.gr has no CNAME records.
Question and response
Question
dig mail.teiath.gr. NS
Answer
The response has no answer records.
Authority
teiath.gr. 8882 SOA hermes.teiath.gr. root.mail.teiath.gr. 2025102700 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0