As of today, Collaboration Protection no longer provides protection for non-email items in Exchange (such as calendar entries, contacts, or tasks). Email protection is not affected and continues to work as before.
We are continuing the transition of customer tenants to the Microsoft Graph API. A portion of tenants have already been moved over, and this process is ongoing. We are closely monitoring the transition, making adjustments as needed, and investigating any issues that arise.
For background on this transition, please see our earlier announcement:
Collaboration Protection: Transitioning Exchange Protection to Microsoft Graph API
Possible known issue
We've identified a small number of cases where an email that was previously quarantined and released using EWS (Exchange Web Services) may appear to be quarantined again after a tenant moves to the Graph API, if item is modified. If an item is re-quarantined this way, an administrator should release the item again.
We're flagging this proactively since it can be confusing if you encounter it. There is no clear, consistent pattern yet for when this happens — it appears to stem from differences in how EWS and Graph API report certain email properties. We expect the number of cases to decrease over time, and we'll continue monitoring closely in the meantime.