nic.swiss has no MX records.
Question and response
Question
dig nic.swiss. MX
Answer
The response has no answer records.
Authority
nic.swiss. 86400 SOA anycast1.irondns.net. dnsmaster.irondns.net. 1543 10800 3000 2419200 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0