_spf.tdc.net has no MX records.
Question and response
Question
dig _spf.tdc.net. MX
Answer
The response has no answer records.
Authority
tdc.net. 3600 SOA auth01.ns.tele.dk. dns.eng.tdc.net. 2024050701 7200 1800 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0