brandshelter.de has no MX records.
Question and response
Question
dig brandshelter.de. MX
Answer
The response has no answer records.
Authority
brandshelter.de. 86400 SOA pdns109.ultradns.com. tech.brandshelter.com. 2020062331 86400 86400 86400 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0