o365relay.prewise.net has no MX records.
Question and response
Question
dig o365relay.prewise.net. MX
Answer
The response has no answer records.
Authority
prewise.net. 3600 SOA ns1.prewise.com. hostmaster.prewise.com. 2020120201 1200 600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0