Accessing Outlook on the web for business using organizational credentials.
Hello @Katie Tropp
From the information you provided, the error usually indicates that the Microsoft 365 tenant has been blocked. This can happen for several reasons, such as a subscription expiration, billing issues, tenant policy restrictions, or administrative actions taken within the Microsoft 365 environment.TenantAccessBlockedException
If you're an end user and don't have access to the Microsoft 365 admin center, the best solution is to contact your organization's global admin directly. Tenant-level issues, such as the error, typically require admin access or Microsoft Support to be investigated and resolved.TenantAccessBlockedException
If you have admin access, please sign in to the Microsoft 365 admin center and verify that the subscription is active and in good standing. Tenant access may be restricted if the subscription has expired or if there is a billing issue.
If the subscription is active and in good standing, the Microsoft 365 global administrator must submit a support request to Microsoft Support. Support engineers have access to advanced diagnostic tools and tenant-level logs that are not accessible through the community forums.
For more information, please see: Get help with Microsoft 365 for business.