Unable to access or use student Outlook mailbox

Question

Hello,

I can no longer access my student mailbox : I am unable to read my emails or send emails, both in Outlook and Outlook Web.

The page shows the error TenantAccessBlockedException / TenantAccessBlockedError.

However, I did not request any mailbox deletion or account change.

If this is a known incident, could you please let me know when the service is expected to be operational again?

This is kind of an urgency because I need access to my university emails.

Answer 1

Hi @Naba,

The TenantAccessBlockedException / TenantAccessBlockedError error usually means that your university’s Microsoft 365 tenant has been blocked at the organizational level. This typically happens due to reasons such as expired or removed licenses, billing or subscription issues, compliance-related actions, or a security‑related block applied by Microsoft.

In this situation, the issue cannot be self‑resolved. The only way forward is to contact your university’s Microsoft 365 administrator, as they’re the only ones with the necessary permissions to review the account status. If you’re not sure who your admin is, this official guide may help you identify the right contact within your school: How do I find my Microsoft 365 admin? - Microsoft Support

Please also note that this is a user‑to‑user community forum. I don’t have access to backend systems or administrative tools, and I’m unable to directly investigate or resolve tenant‑level issues. Since this account is provided and fully managed by your university, only their admin team can perform the required checks and corrective actions.

That said, I truly hope this information helps point you to the right support team so the issue can be reviewed and resolved as quickly as possible.

If you have any updates, feel free to comment back. I’ll be glad to continue the discussion with you. Thank you for your understanding.  

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Answer 2

TenantAccessBlockedException / TenantAccessBlockedError indicates that access to the mailbox has been blocked at the tenant (organization/university) level, not that the mailbox was deleted by the user.

This can only be resolved by the organization that owns and manages the tenant. For a student mailbox, that is the university’s IT or Microsoft 365 administrator. End users cannot clear this condition themselves.

Action steps:

1. Contact the university IT/helpdesk immediately and provide the exact error text: TenantAccessBlockedException / TenantAccessBlockedError and confirm that it affects both Outlook desktop and Outlook on the web.
2. Ask them to check the status of the Microsoft 365 tenant and your account in the Microsoft 365 admin center (for example, whether the tenant is blocked/suspended, or if your account/mailbox has been restricted).
3. If the tenant is in good standing but the mailbox remains blocked, the university admin must open a support case with Microsoft 365 support from the admin portal so Microsoft can investigate and remove the block at service level.
4. Until the tenant block is removed, there is no client-side workaround (changing apps, browsers, or devices will not help), and access to Outlook on the web and Outlook clients will remain unavailable.

Because this is a tenant-level restriction, only the university’s administrators and Microsoft support can provide an ETA or confirm if there is a broader incident.

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References:

• Error when opening classic Outlook: "Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed."