apollon.swiss-server.net has no MX records.
Question and response
Question
dig apollon.swiss-server.net. MX
Answer
The response has no answer records.
Authority
swiss-server.net. 86400 SOA ns1.swiss-server.net. dns.hoonix.com. 2018121604 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0