These known issues may affect your experience with modern email authentication:
On the native calendar app for iPhone, you receive reminders for all calendars added to your device before the change to modern email authentication. Note: you only see the details of a calendar reminder if you already had that level of access to the calendar.
|Turn off these reminder settings on the local app.
|You cannot access Mac Mail on your Mac after the change to modern email authentication.
|This issue can occur if you use a supported macOS version (10.14 or later), but your email was set up before September 2018. You may need to rebuild your Mac Mail profile following these instructions to Configure Apple Mail for Office 365.