mundoeducacao.com has no MX records.
Question and response
Question
dig mundoeducacao.com. MX
Answer
The response has no answer records.
Authority
mundoeducacao.com. 3600 SOA a10-dns-uolcsfe1.host.intranet. root.uol.com.br. 86 7200 3600 432000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0