solo.vivo.com.br has no MX records.
Question and response
Question
dig solo.vivo.com.br. MX
Answer
The response has no answer records.
Authority
vivo.com.br. 900 SOA aquarius.vivo.com.br. root.vivo.com.br. 2014084545 10200 3600 604800 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0