smtp.sendsay.ru has no MX records.
Question and response
Question
dig smtp.sendsay.ru. MX
Answer
The response has no answer records.
Authority
sendsay.ru. 600 SOA ns.iprojects.ru. noc.iprojects.ru. 2023051521 10800 1100 864000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0