Compliance Problems

How to Clean Up Exchange Mailboxes Larger Than 100 GB

Maira Mehtab Oct 9, 2026 869 views

Question details

The user needs to clean up a Microsoft Exchange mailbox that has exceeded the 100 GB limit, but manual deletion is prevented by compliance policies and deprecated commands.

How to Clean Up Exchange Mailboxes Larger Than 100 GB

Product: Microsoft Exchange
Device & OS: not provided
Scenario: Trying to free up storage space in a massive mailbox where items are stuck in user folders and Recoverable Items due to retention policies.
Observed behavior: Manual deletion is blocked by retention policies, compliance actions fail to execute, and deprecated PowerShell commands are no longer available to forcefully remove data.

Before you start

Before taking action, ensure you have global administrator or Exchange administrator privileges in the Microsoft 365 admin center, and verify if the affected mailbox is currently under a litigation hold.

Solution 1Recommended

Create a Service Request in the Microsoft 365 Admin Center

Because backend permissions and strict compliance retention policies are blocking manual deletion, the safest and most effective method is to engage Microsoft Support to assist with the cleanup.

When a mailbox exceeds 100 GB, the excess data is often locked inside the Recoverable Items folder due to litigation holds or organization-wide retention policies.

Since legacy PowerShell commands like Search-Mailbox have been deprecated and standard compliance actions may time out or fail on mailboxes of this size, Microsoft support engineers must intervene to temporarily adjust holds and safely clear the backend data.

Log in to the Admin Center

Navigate to the Microsoft 365 admin center (admin.microsoft.com) and log in using your administrator credentials.

Navigate to Service Requests

On the left-hand navigation menu, click on 'Support' and then select 'Service requests' or 'Help & support'.

Open a New Ticket

Click 'New service request'. In the description box, detail that your Exchange mailbox exceeds 100 GB, is blocked by retention policies, and compliance actions are failing.

Submit for Investigation

Submit the ticket. Microsoft support engineers will review the backend mailbox retention, litigation hold status, and Recoverable Items permissions to provide a secure cleanup path.

Create a Service Request in the Microsoft 365 Admin Center

Avoid Bulk Deletion Attempts: Do not attempt unauthorized bulk deletions or untrusted script workarounds until Microsoft support confirms your compliance requirements, as this may lead to permanent data loss or auditing violations.

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Frequently Asked Questions

Why can't I manually delete emails from a 100 GB Exchange mailbox?

If the mailbox is under a retention policy or litigation hold, compliance settings prevent the permanent deletion of messages. Instead of being deleted, the items are routed to a hidden Recoverable Items folder, keeping the storage usage high.

What is the Recoverable Items folder in Microsoft Exchange?

It is a hidden folder in Exchange that stores deleted items for compliance, eDiscovery, and recovery purposes. When a mailbox has strict retention policies, this folder retains data indefinitely, which often causes the mailbox to hit the 100 GB storage limit.

Can I use PowerShell to clean up an oversized Exchange mailbox?

Legacy PowerShell commands like Search-Mailbox have been deprecated by Microsoft. While you can use Compliance Search or Content Search commands, these will still fail if backend retention policies are actively locking the data, which is why contacting Microsoft support is recommended.

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