Check Service health for your tenant
In the Microsoft 365 admin centre, open Health → Service health. A tenant is the Microsoft 365 environment that holds your organisation’s accounts and services. Check EX1550543 for Exchange Online and MO1550821 for other Microsoft 365 services. If you can’t sign in, use Microsoft’s public status page. Use your tenant’s incident record when filing.
Recover delayed email and keep working
Test Outlook on the web with a known working external address. Check shared mailboxes, the Outbox and nondelivery reports before resending. Ask an Exchange administrator to run a message trace with the sender, recipient, timestamp and message ID. Use an independent phone or CRM channel for time-sensitive work.
Where to submit an SLA credit request
If Microsoft bills you directly, open Help & support in the Microsoft 365 admin centre. If a Cloud Solution Provider (CSP) bills you, use the support channel on your invoice. Ask who files the credit request and when. Microsoft gives the submitting CSP one month from the end of the affected billing month to file a Microsoft 365 request. A reseller may need the evidence earlier. For direct billing, check the deadline in your contract.
What to include in the support case
Include the tenant ID (the GUID on the Microsoft Entra admin centre Overview page), the incident ID, the affected workload and billing reference. Keep start and end times, licensed and affected user counts, locations, webmail errors, message traces and the support case number. Record lost orders and staff costs separately for review under your contract or insurance.
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Exchange Online credit thresholds
For standard Exchange Online webmail availability, qualifying user-minutes determine monthly uptime. The service-credit tiers are 25% below 99.9%, 50% below 99% and 100% below 95%, on eligible fees. Six hours of downtime affecting everyone in a 30-day month gives roughly 99.17%. If one user in ten was affected, it gives roughly 99.92%. Mail-delivery delays have separate metrics.
Alternatives and continuity
Pilot Google Workspace, Zoho Workplace or Proton for Business with real shared mailboxes, calendars, retention and spreadsheets. If you keep Exchange Online, test a separately hosted continuity service with an independent sign-in. Plan MX, SPF, DKIM and DMARC changes and a rollback before switching.