mx4.otenet.gr has no CNAME records.
Question and response
Question
dig mx4.otenet.gr. NS
Answer
The response has no answer records.
Authority
otenet.gr. 5105 SOA ns1.otenet.gr. hostmaster.ns1.otenet.gr. 2026021101 10800 3600 1814400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0