clases.net.do has no MX records.
Question and response
Question
dig clases.net.do. MX
Answer
The response has no answer records.
Authority
clases.net.do. 7200 SOA dns1.midominio.do. leonardo.codetiger.co. 2026012801 7200 7200 172800 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0