ns4.site.pro has no MX records.
Question and response
Question
dig ns4.site.pro. MX
Answer
The response has no answer records.
Authority
site.pro. 300 SOA ns1.site.pro. support.site.pro. 2026021101 1200 300 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0