Not Able to log in and use email outlook

Have a Microsoft 365 administrator check Health → Service health immediately, because an organization-wide failure affecting Outlook, Teams, and Microsoft 365 web sign-in must first be distinguished from an active Microsoft incident.

1. Check your tenant’s current service status

1. Sign in to the Microsoft 365 admin center with a Global Admin, Service Support Admin, or Helpdesk Admin account.
2. Open Health → Service health.
3. Under Active issues Microsoft is working on, inspect incidents involving:
   • Exchange Online
   • Microsoft 365 suite
   • Microsoft Teams
   • Microsoft Entra authentication
4. Open the incident and check Status, User impact, All updates, and the next scheduled update.

Service health is tenant-specific and provides Microsoft’s current investigation and recovery information. The restoration time cannot be estimated from the spinning screen; use the incident’s latest update for the available timeline.^1^

If an incident is listed, avoid changing passwords, reinstalling applications, or modifying tenant policies. Monitor the incident until its status becomes Service restored.

2. If the admin center also will not open

Use Microsoft’s public service status page from a different Internet connection or mobile device. Microsoft documents this as the backup when an incident prevents access to the admin center.^1^

This public page is less tenant-specific than the Microsoft 365 Service health dashboard. If possible, also have an emergency administrator try the admin center from:

• A mobile-data connection rather than the company network.
• A device not connected to the company VPN or proxy.
• A private browser window.

This separates a company-network or browser-session problem from a wider Microsoft 365 failure.

3. If Service health shows no incident

An administrator who can reach the Microsoft Entra admin center should inspect the failed authentication events:

1. Open Entra ID → Monitoring & health → Sign-in logs.
2. Filter by the failure time and one affected user.
3. Open the event and review:
   • Failure reason
   • Authentication Details
   • Conditional Access
   • Troubleshooting and support
4. If Conditional Access caused the interruption, select the policy name to identify the exact control that blocked access.

Microsoft specifically warns that policies targeting all users and all resources can block the entire organization—for example, a blanket block or compliance requirement.^2^

Do not disable security policies broadly without identifying the matching failed sign-in event first.

4. Report or escalate the outage

If no relevant incident appears:

• In Health → Service health, select Report an issue. This lets Microsoft correlate reports from multiple organizations.^1^
• Alternatively, an administrator can select Help & support, describe that all users cannot access Outlook, Teams, or Microsoft 365, and then select Contact Support.^3^
• If the subscriptions were purchased entirely through a Microsoft partner, contact that partner for support.^3^

Include the outage start time, affected services, number of users, whether mobile data works, and any request/correlation IDs from Entra sign-in logs. Do not post passwords, verification codes, tenant IDs, or user details publicly.

References

1. How to check Microsoft 365 service health
2. Troubleshoot sign-in problems with Conditional Access
3. Get support for Microsoft 365 for business