_spf.smtplw.com has no MX records.
Question and response
Question
dig _spf.smtplw.com. MX
Answer
The response has no answer records.
Authority
smtplw.com. 3600 SOA ns1.locaweb.com.br. hostmaster.locaweb.com.br. 2023100304 3600 600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0