mx5.t21v.ru has no MX records.
Question and response
Question
dig mx5.t21v.ru. MX
Answer
The response has no answer records.
Authority
t21v.ru. 100 SOA ns1.t21v.ru. mail.t21v.ru. 2025112601 900 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0