ru-out.promdns.net has no MX records.
Question and response
Question
dig ru-out.promdns.net. MX
Answer
The response has no answer records.
Authority
promdns.net. 3600 SOA ns.promdns.net. noc.uaprom.net. 2026022601 43200 7200 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0