smtp.SSNDSY.RU has no MX records.
Question and response
Question
dig smtp.SSNDSY.RU. MX
Answer
The response has no answer records.
Authority
SSNDSY.RU. 3600 SOA ns.iprojects.RU. noc.iprojects.RU. 2019091301 10800 1100 864000 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0