nexus.sudomemo.net has no MX records.
Question and response
Question
dig nexus.sudomemo.net. MX
Answer
The response has no answer records.
Authority
sudomemo.net. 1800 SOA bowen.ns.cloudflare.com. dns.cloudflare.com. 2395298584 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0