Microsoft Outlook "Windows Security" message request Sign In
Outlook 2013 and 2016 client configured for UW O365 continues to receive Window Security sign in window requesting user authentication. The windows security message and sign in request is attempting to connect to another calendar or internet calendar, delete the calendar.
Go to account settings, select the "Internet Calendars" tab, see if there are subscribed calendars and "remove" the calendar:
1. While Outlook is open, go to the "File" menu.
2. Select "Account Settings"
3. At the Account Settings, windows go to the "Internet Calendars" tab.
4. Review linked calendars and remove...