mxs1.reg.RU has no MX records.
Question and response
Question
dig mxs1.reg.RU. MX
Answer
The response has no answer records.
Authority
reg.RU. 10800 SOA ns1.reg.RU. hostmaster.ns1.reg.RU. 1772272013 14400 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0