ns2.rr64.com.br has no MX records.
Question and response
Question
dig ns2.rr64.com.br. MX
Answer
The response has no answer records.
Authority
rr64.com.br. 21600 SOA ns1.rr64.com.br. suporte.rr64.net. 2026011502 3600 1800 86400 21600
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0