mx1.swe.sonera.net has no CNAME records.
Question and response
Question
dig mx1.swe.sonera.net. NS
Answer
The response has no answer records.
Authority
sonera.net. 7733 SOA namesurfer.inet.fi. hostmaster.telia.fi. 2025121607 28800 7200 3456000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0