pbx.simtelecom.com.br has no MX records.
Question and response
Question
dig pbx.simtelecom.com.br. MX
Answer
The response has no answer records.
Authority
simtelecom.com.br. 300 SOA dns1.commcorp.net.br. postmaster.commcorp.com.br. 2022102255 7200 900 1296000 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0