Microsoft 365 outage – Outlook not sending or receiving emails across three business accounts Copy title

The incidents must be confirmed in each business tenant’s Microsoft 365 Service health dashboard, where the current scope, status, restoration estimate, and Microsoft updates for EX1550543 and MO1550821 are authoritative.

There is also a date discrepancy: today is 12 November 2026, while the issue is described as starting 13 November 2026. Confirm the intended start date and time zone when opening a support case.

Confirm the incidents and restoration status

A Microsoft-hosted public report associates:

• EX1550543 with an Exchange Online incident.
• MO1550821 with a broader Microsoft 365 incident involving multiple services.

However, the public information does not establish an Australia-only outage or prove that every affected tenant is included. Tenant-specific confirmation is required. ^1^

For an administrator of each of the three business tenants:

1. Sign in to the Microsoft 365 admin center.
2. Go to Health → Service health.
3. Under Active issues Microsoft is working on, open EX1550543 and MO1550821 if listed.
4. Check User Impact, Affected services, Status, All Updates, and any estimated next-update or restoration time.
5. Check Issue history if an incident no longer appears as active.
6. If the symptoms continue but neither incident appears, select Report an issue from Service health.

Service health is tenant-aware and shows whether an incident applies to that organization. The incident details contain Microsoft’s latest status and progress updates; there is no independently supported restoration time beyond what is posted there. If the admin center cannot be reached, use Microsoft’s public service-status page referenced in the same documentation. ^2^

Because Outlook fails across laptop and mobile and Word also cannot upload, avoid reinstalling Outlook or recreating profiles while a matching service incident remains active.

Will delayed email eventually arrive?

Do not assume that every message will be delivered. The result depends on whether Exchange Online accepted the message and whether the sending system continues retrying.

Use message trace to determine what happened:

1. Open Microsoft 365 admin center → Exchange.
2. Go to Mail flow → Message trace.
3. Search using an affected recipient, sender, and the relevant date range.
4. Open each result and inspect its status and details:
   • Delivered: Exchange Online delivered it to the mailbox.
   • Pending or delayed: monitor it after service recovery.
   • Failed: inspect the error and any non-delivery report (NDR).
   • No trace: the message might not have reached your Exchange Online organization.

Message trace data can take from approximately 10 minutes to one hour to appear. Microsoft’s delivery troubleshooting documentation also provides Diag: Troubleshoot Email Delivery in the admin center for administrators. ^3^

If a sender receives an NDR, the message was not delivered; preserve the complete NDR and SMTP status code for the support case. ^4^

Protect the Word changes

For the specific Upload Pending state:

1. Leave Word open.
2. Keep AutoSave enabled.
3. Maintain network connectivity.
4. Wait for Word to retry the upload in the background.

Microsoft documents that Upload Pending means the document cannot currently be saved to the server and that Word retries while it remains open with AutoSave enabled. ^5^

For business-critical edits, also save a separate local copy under a different filename before closing Word. Do not discard pending changes.

Escalate to Microsoft Business Support

If the incidents are absent from Service health, shown as restored while failures continue, or only some tenants remain affected:

1. In each affected tenant, open the Microsoft 365 admin center.
2. Select Help & support at the lower right.
3. Describe the issue, including:
   • EX1550543 and MO1550821
   • Correct start date, local time, and time zone
   • Three affected businesses/tenants
   • Desktop and mobile impact
   • Word Upload Pending error
   • Example sender, recipient, timestamp, message ID, and NDR codes
4. Select Contact Support, choose phone or email, and submit the request.
5. Open separate requests for the Exchange mail-flow issue and Word/SharePoint or OneDrive upload issue.

An admin is required. Direct Microsoft support requires at least one subscription purchased from Microsoft; if every subscription was purchased through a partner, contact that partner instead. ^6^

References

1. Looking for a responce from Microsoft on Outage
2. How to check Microsoft 365 service health
3. Find and fix email delivery issues as a Microsoft 365 for business admin
4. Email non-delivery reports and SMTP errors in Exchange Online
5. [Mac](https://support.microsoft.com/word/troubleshoot-common-coauthoring-errors#upload-failed-resolve-conflict)
6. Get support for Microsoft 365 for business