reserved.default-host.net has no MX records.
Question and response
Question
dig reserved.default-host.net. MX
Answer
The response has no answer records.
Authority
default-host.net. 60 SOA ns1.fastdns.hosting. hostmaster.adm.tools. 2026022235 43200 7200 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0