If I was in your IT department I'd be required to shut this down and probably revoke your access until our bosses decide on your future.
Keep in mind, your employer has a responsibility to protect their data and this would subject your homelab to any legal liabilities such as a lawsuit search order and data privacy auditing.
Any solution you work out needs to be signed off on in writing if it's outside their expected usage.
Another important point o365 requires oauth2 authentication unless your IT department has intentionally allowed other forms of authentication or they are in a hybrid legacy environment.
When they broke EWS and office 2010 compatibility they crippled many foss solutions without an additional license and the tools that do work will report details to exchange about your homelab. So if your department is diligent it'll come to their attention.