de.telia.net has no MX records.
Question and response
Question
dig de.telia.net. MX
Answer
The response has no answer records.
Authority
de.telia.net. 3600 SOA dns1.telia.com. backbone.telia.net. 2019060700 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0