smtp6.hoster.ru has no MX records.
Question and response
Question
dig smtp6.hoster.ru. MX
Answer
The response has no answer records.
Authority
hoster.ru. 1800 SOA ns10.hoster.ru. support.hoster.ru. 3509107393 3600 300 604800 1800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0