ns4.spaceweb.pro has no MX records.
Question and response
Question
dig ns4.spaceweb.pro. MX
Answer
The response has no answer records.
Authority
spaceweb.pro. 600 SOA ns3.spaceweb.pro. postmaster.sweb.ru. 2015112510 28800 7200 604800 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0