comm.assistant.ua has no MX records.
Question and response
Question
dig comm.assistant.ua. MX
Answer
The response has no answer records.
Authority
assistant.ua. 1800 SOA nsa4.srv53.net. support.dnshosting.org. 1764677036 1800 600 2419200 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0