More info: Impacted connection methods include, but may not be limited to: – Outlook.com – Outlook Mobile – Outlook desktop client Current status: Our deployment of the fix is progressing quicker than anticipated and we expect impact to gradually mitigate as it progresses. We believe the issue will be resolved by our next update time.

https://answers.microsoft.com/en-us/outlook_com/forum/all/i-cant-log-in-to-my-hotmailcom-or-outlook-email/cd3b88e9-a8f6-4b56-9d31-f5706381bcbe