ns1.seo.r1servers.com has no MX records.
Question and response
Question
dig ns1.seo.r1servers.com. MX
Answer
The response has no answer records.
Authority
seo.r1servers.com. 86400 SOA ns1.seo.r1servers.com. office.hostbulgaria.com. 2026022301 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0