sites.ifsc.usp.br has no MX records.
Question and response
Question
dig sites.ifsc.usp.br. MX
Answer
The response has no answer records.
Authority
ifsc.usp.br. 300 SOA deneb.ifsc.usp.br. scinfor.ifsc.usp.br. 2026030565 7200 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0