outlook.ms-acdc.office.com has no MX records.
Question and response
Question
dig HHN-efz.ms-acdc.office.com. MX
Answer
The response has no answer records.
Authority
ms-acdc.office.com. 60 SOA ns1-ms-acdc.office.com. hostmaster.microsoft.com. 2055339175 900 600 86400 60
Additional
. 0 OPT ; payload 1224, xrcode 0, version 0, flags 0