mail.SIBPGT.RU has no MX records.
Question and response
Question
dig mail.SIBPGT.RU. MX
Answer
The response has no answer records.
Authority
SIBPGT.RU. 600 SOA ns4-cloud.nic.RU. sibpgt.bk.RU. 2023091240 1440 36000 2592000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0