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TenantAccessBlockedError is a frequently encountered issue that usually indicates a temporary lock on your Microsoft 365 organization which restricts access to services such as your Outlook mailbox. Here are some steps you may take to help resolve your issue:
1.Check account status and payments:
Sign in to the Microsoft 365 admin center > Billing > Bills & Payments. > Check for unpaid bills. If there is an unpaid bill, pay it immediately.
2.Check the service status to see if there are any service outages or advisories that may explain the current issue.
3.After trying this and your issue still persists, please raise a ticket at Microsoft 365 admin center > Help & Support
If you're not a tenant admin, contact your IT admin. They can check the reason and take appropriate action to unlock.
If you have any other questions, feel free to ask.
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