Urgent: Outlook Email Sending Issue – HTTP Error 500

The Outlook HTTP 500 error reported on 13 November 2026 coincides with a widespread Microsoft 365 service disruption, so check the applicable Microsoft service-health dashboard and track recovery rather than changing mailbox settings first.^1^

Check the incident status

If this is a personal Outlook.com account:

1. Open the Microsoft service-status page.
2. Expand Microsoft’s Consumer Products → Outlook.com.
3. If Outlook.com shows an active incident, wait for the status to become restored and then retry. Microsoft directs Outlook.com access failures to this status page.^2^

If the address is managed by your company through Microsoft 365:

1. Ask a Microsoft 365 administrator to sign in to the Microsoft 365 admin center.
2. Select Health → Service health.
3. Open any active Exchange Online incident and review User impact, status, and Microsoft’s latest update.
4. Select Manage notifications for this issue to receive recovery updates.

An active incident means a service or major function may be unavailable, including sign-in and sending or receiving email.^3^

A backend outage can affect Outlook.com, mobile, and desktop clients simultaneously, so switching applications might not provide a workaround. Use another communication channel for urgent client messages until Microsoft reports restoration.

If service health shows no incident

Determine whether the failure is browser-specific:

1. Open an InPrivate/Incognito window and sign in to Outlook.
2. If Outlook works there, clear the normal browser’s Outlook/Microsoft cookies and cached data for All time, close the browser, and sign in again.
3. If it still fails, test another supported browser and another network or device.

An HTTP 500 that persists across different browsers, devices, and networks points away from a local browser-session problem. If only this mailbox fails while another account works on the same device, proceed to account support rather than resetting the computer.

Check account conditions after access returns

If Outlook opens but sending and receiving still fail:

• Check Microsoft cloud and mailbox storage. When storage is full, Outlook.com cannot send or receive messages; incoming messages during that period can be rejected and are not recoverable.
• Check whether the account has been temporarily blocked following unusual sign-in activity.
• If the password was recently changed, update the saved credentials in connected Outlook applications.
• For an individual sending failure, remove any attachment larger than 25 MB and retry.^4^

Escalate if no incident is listed

• Microsoft 365 administrator: On Health → Service health, select Report an issue and submit the affected service, start time, HTTP 500 message, and number of affected users. Reported issues can be correlated with reports from other organizations.^3^
• Outlook.com user: If Outlook opens, select Help, enter the problem, then choose Still need help? → Yes. If sign-in remains impossible, use Microsoft’s Outlook.com contact-support route documented on the send/receive support page.^4^

Include the exact occurrence time and time zone, affected account type, screenshot with personal information hidden, browsers/devices tested, and whether other users in the organization are affected.

References

1. Widespread Microsoft outage takes down Outlook and other 365 services
2. Fixes or workarounds for recent issues on Outlook.com | Microsoft Support
3. How to check Microsoft 365 service health
4. Can't send or receive email in Outlook.com | Microsoft Support