mail.von-oppen.com has no MX records.
Question and response
Question
dig mail.von-oppen.com. MX
Answer
The response has no answer records.
Authority
von-oppen.com. 1800 SOA von-oppen.com. marko.von-oppen.com. 2024030101 10800 1800 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0