s3.valfman.ru has no MX records.
Question and response
Question
dig s3.valfman.ru. MX
Answer
The response has no answer records.
Authority
valfman.ru. 1800 SOA ed.ns.cloudflare.com. dns.cloudflare.com. 2395636588 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0