_spf.corp.m.unr.com has no MX records.
Question and response
Question
dig _spf.corp.m.unr.com. MX
Answer
The response has no answer records.
Authority
unr.com. 300 SOA ns02.trs-dns.com. trs-ops.tucows.com. 2026021112 3600 300 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0