Just a heads up. As of yesterday, Microsoft prematurely disabled basic authentication on our O365 tenant. This caused IMAP mail fetching to stop working in osTicket. Although this isn't supposed to be deprecated until October. After talking with Microsoft support, supposedly they made a mistake while testing, and they disabled basic auth on many O365 tenants across the globe. I saw a lot of complaints on this all over the internet yesterday. They were able to assist with turning basic authentication back on, but warned it may be shut off again before October.
Anyways, just wanted to give everyone a heads up, and hoping for a stable release soon!