Microsoft Outlook is DOWN for all company Users

Question

Our Microsoft 365 Outlook is down for all users. It is not a WiFi connectivity issue. We normally access through the browser.

Answer 1

Hi @Robert Faison, 

Thank you for posting your question in the Microsoft Q&A forum. 

Regarding the issue where you are unable to access the Microsoft 365 Admin Center and other Microsoft 365 services, there have been no official reports indicating a widespread outage at this time. 

To resolve this, Microsoft’s support team will need to step in. A technical support engineer can perform a remote session to investigate the situation verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.   

For additional assistance, use this link to find the appropriate contact number: Global Customer Service phone numbers - Microsoft Support   

 If your Office 365 subscriptions are managed through a federated partner or reseller and the Global Admin cannot open a service request, they should contact the reseller’s support provider. The reseller can assist with initiating the request and coordinating with the Office 365 support team.     

I apologize for redirecting you, but moderators in this community have limited access to backend systems. Contacting the official support team is the fastest way to receive effective assistance. 

Thank you again for your time and understanding. I really appreciate your patience, and I’m here to help. Looking forward to your response.    

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Answer 2

I am unable to sign in to the Microsoft 365 Admin Center as the company administrator. I am unable to log in to any Microsoft 365 platforms - Outlook, One Drive, Forms, etc.

Answer 3

For an outage affecting all users in the organization, the most likely causes are a Microsoft 365 service issue or a broader Microsoft network issue.

Perform these checks in order:

1. Have a Microsoft 365 admin check Exchange Online service health
   • Sign in to the Microsoft 365 admin center.
   • Go to Service health and review the status for Exchange Online and related services.
   • If an incident or advisory is listed, follow the guidance and updates provided there. This confirms a service-side issue.
2. Check Microsoft 365 global network health
   • Review the current Microsoft 365 network health status to see if there are any significant global or regional issues impacting connectivity to Microsoft 365 services.
   • If issues are listed for your region, this can explain why Outlook on the web is down for all users.
3. Validate local network/firewall configuration
   • Even if Wi‑Fi is working, a firewall or proxy change can block Microsoft 365 endpoints for the whole company.
   • Compare any recent firewall/proxy changes with the timing of the outage.
4. If no service incident is reported and no local network changes are found
   • Run the Microsoft 365 diagnostics (admin) for Outlook/Exchange connectivity from the Troubleshooting tools in the admin center to confirm whether the tenant can reach Exchange Online.
   • If the diagnostics do not identify a configuration issue, open a support ticket from the admin center so Microsoft can check the tenant and backend service.

Until service health or network health shows green and users can sign in again, the issue is almost certainly not client-side, given that it affects all users and access via browser.

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References:

• Fix Outlook connection problems for Microsoft 365 account
• Microsoft 365 network health status
• Outlook performance is slow in the Microsoft 365 environment