Microsoft has confirmed that the issue has been resolved. If you still see an issue, please restart your Outlook client for the changes to take affect.
The latest update from Microsoft says the vast majority of customers have received the fix but a subset are still having issues and may need to restart Outlook client.
Current status: We've identified the probable cause of the issue and are applying fixes. We've confirmed that our fixes are effective and users will experience service restoration as our solution reaches their respective environments; however, deployment to all affected users may take several hours to complete.
Some users are experiencing Outlook connection issues and crashes with the Outlook desktop client. Microsoft is aware of the issue and is working on a solution.
Users experiencing this issue can still access their email using the Outlook Web client (https://office365.uiowa.edu) or Outlook mobile client.