Check your tenant in Service health
In the Microsoft 365 admin centre, go to Health → Service health. Your tenant is your organisation’s separate Microsoft 365 environment. Look for EX1550543 and MO1550821. Use Microsoft’s public status page if you cannot sign in.
Canadian media covered the global incident. Record the status and actual service interruption for your tenant. Use a precise time zone, since Canadian offices may be spread across several zones.
Recover delayed mail and keep working
Test Outlook on the web and email in both directions with an external account. Check shared mailboxes, the Outbox and nondelivery reports before resending. Ask an Exchange administrator to run a message trace using sender, recipient, timestamp and message ID.
Route time-sensitive business through a working phone number or an independently accessible CRM. Open a separate case if errors remain after recovery.
Ask the invoice provider for a credit
Use Help & support if Microsoft invoices you directly. If a Canadian reseller invoices you, ask it to file or escalate via its Cloud Solution Provider (CSP) distributor.
The Microsoft CSP rule for Microsoft 365 gives the submitting partner one month after the affected billing month. Ask for the supplier’s earlier intake deadline and case number. Ask how an approved credit will appear on your bill, and check the deadline in your direct Microsoft contract if applicable.
Sherweb · If your Canadian reseller sources the subscription through Sherweb, ask the reseller to open the partner ticket and confirm the intake deadline.
Evidence for the support ticket
Include the tenant ID (the GUID on the Microsoft Entra admin centre Overview page), incident ID, affected workload, subscription, and invoice reference.
Record the start and end times with zones, affected and licensed user counts, webmail errors, message traces and Service health notices. Keep business losses in a separate record for contract or insurance review.
Exchange Online credit thresholds
The standard webmail availability SLA uses qualifying user-minutes. Monthly uptime below 99.9%, 99% and 95% corresponds to credits of 25%, 50% and 100% of eligible charges. Six hours of downtime for everyone in a 30-day month is roughly 99.17%; affecting one in ten users gives about 99.92%.
Mail delivery delay has a separate measure. Record each affected workload separately and confirm eligible charges with the supplier.
Alternatives and continuity planning
Pilot Google Workspace, Zoho Workplace or Proton for Business with shared mail, calendars, Excel workflows and retention. Review data location and your organisation’s privacy obligations.
Consider a separately hosted email continuity service with independent authentication. Test it before a disruption and plan MX, SPF, DKIM and DMARC changes and rollback before any migration.