mail.nwinternet.com has no MX records.
Question and response
Question
dig mail.nwinternet.com. MX
Answer
The response has no answer records.
Authority
nwinternet.com. 3600 SOA ns1.nwinternet.com. hostmaster.nwinternet.com. 2024080900 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0