nso23.o365filtering.com has no MX records.
Question and response
Question
dig nso23.o365filtering.com. MX
Answer
The response has no answer records.
Authority
o365filtering.com. 60 SOA ns1-32.azure-dns.com. hostmaster.o365filtering.com. 2024072206 10800 3600 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0