mail.byggvir.de has no MX records.
Question and response
Question
dig mail.byggvir.de. MX
Answer
The response has no answer records.
Authority
byggvir.de. 150 SOA ns3.stratoserver.net. hostmaster.strato-rz.de. 2020051302 86400 7200 604800 300
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0