Resolved - Conditional access unexpectedly blocking macOS 10.15.4 native mail client/other apps

Thanks Intune_Support_Team , I hope the team can provide more details and advise about how we can fix the issue asap.   There had MacOS Mail issue with Office 365 Exchange from 10.15.4, sadly in original issue is fixed in 10.15.5, but the mentioned new issue is happened.

On Apple side they said MS updated something on Office 365, what they said is "a security settings in o365 that blocks it's content to be shown in the mac mail server. And the same reason that affects the other old emails on the local folders because there's exchange emails on the same folder."

Our client had a local Mailbox (Folder) created in MacOS Mail very long time ago, she was using NetSol email system with POP connection before.  Few months ago we helped to migrate to Office 365.  The local Mailbox (Folder) used to keep the emails which from NetSol and also Office365. Not sure how it can define it is email from exchange but the issue start to appear after 10.15.4 MacOS update.   It will be nice if someone can let us know which security setting has been updated on Office 365 during Apple release 10.15.4 and 10.15.5 update, then we can try to enable/disable for testing.