Microsoft Outlook email not working

Check Microsoft 365 service health first; if no Exchange Online or sign-in incident is listed, test another browser, device, and network to isolate a local browser, DNS, proxy, or firewall problem.

1. Check for a Microsoft 365 outage

• Business account administrator: Sign in to the Microsoft 365 admin center, then open Health → Service health. Review Exchange Online and Microsoft 365 web/sign-in incidents.
• If the admin center will not open: Check the public Microsoft service status page.
• Non-administrator: Ask your Microsoft 365 administrator to perform the first check.

An active incident means Microsoft is already investigating; open it to see impact, updates, and any workaround. If the problem is absent, an administrator can select Report an issue from Service health. ^1^

2. Isolate browser versus network access

Try these in order:

1. Open Microsoft 365 in an InPrivate/Incognito window.
2. Try a different supported browser.
3. Try the same page from another device on the same network.
4. Connect the device to another network, such as a mobile hotspot, and try again.

Interpret the result:

• Works in private browsing: Clear the normal browser’s Microsoft cookies/site data and disable browser extensions that filter traffic.
• Works on another device but not this one: The problem is local to the original device or browser.
• Works through a hotspot but not the normal network: Check that network’s DNS, proxy, VPN, firewall, or web-filtering configuration.
• Fails on every device and network: Recheck Service health and have the administrator report the issue.

Testing Microsoft 365 through another browser or private session is also an established way to distinguish account availability from local cached sign-in or device issues. ^2^

3. If the normal network is the only failure

Temporarily disconnect any VPN and retry. If this is an organizational network, ask its administrator to check whether the proxy or firewall permits outbound TCP/HTTPS traffic on ports 80 and 443 to Microsoft 365 destinations, including *.microsoftonline.com and *.outlook.com. Microsoft documents restricted connectivity and authentication proxies as possible reasons Microsoft 365 pages and clients cannot sign in. ^3^

If ordinary websites also display “site can’t be reached,” troubleshoot the Internet connection or DNS before changing Outlook settings. Reinstalling Microsoft 365 or modifying the Outlook profile is unlikely to fix a login webpage that cannot be reached.

4. Escalation

If there is no listed incident and the page fails across different browsers, devices, and networks:

• Business Microsoft 365: The administrator should use Health → Service health → Report an issue.
• Personal Outlook.com: Open Outlook.com support, select Help, enter the problem, then scroll to Still need help? → Yes. If sign-in itself is unavailable, use the alternate support option documented on Microsoft Support. ^4^

When escalating, provide the exact unreachable address, complete browser error text, approximate start time, affected devices/networks, and whether the public service-status page loads. Do not post account details publicly.

References

1. How to check Microsoft 365 service health
2. Microsoft 365 won't load - Microsoft Q&A
3. How to troubleshoot non-browser apps that can't sign in to Microsoft 365, Azure, or Intune | Microsoft Support
4. [Outlook on the web](https://support.microsoft.com/outlook/add-a-calendar-in-outlook-com-or-outlook-on-the-web#still-need-help)