mxs.mail.ru has no MX records.
Question and response
Question
dig mxs.mail.ru. MX
Answer
The response has no answer records.
Authority
mxs.mail.ru. 3600 SOA ns1.mail.ru. hostmaster.mail.ru. 3436238079 1800 900 604800 3600
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0