mx.comteam.at has no CNAME records.
Question and response
Question
dig mx.comteam.at. NS
Answer
The response has no answer records.
Authority
comteam.at. 30 SOA sec1.rcode0.net. rcodezero-soa.ipcom.at. 2026020901 10800 3600 604800 30
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0