Exchange Connection Problems

How to Restore Access to a Deleted Shared Mailbox in Microsoft 365

Rana Garcia Oct 7, 2026 869 views

Question details

The user needs to restore user access to a shared mailbox that was accidentally deleted, recovered, and subsequently became inaccessible after a password was assigned.

How to Restore Access to a Deleted Shared Mailbox in Microsoft 365

Product: Microsoft 365 / Exchange Online
Device & OS: not provided
Scenario: Recovering an accidentally deleted shared mailbox and re-establishing standard delegated access so team members can view it without requiring a dedicated Exchange Online license.
Observed behavior: The shared mailbox became inaccessible because assigning a password during restoration inadvertently required direct sign-in, which conflicts with the unlicensed delegated access model.

Before you start

Ensure you have Exchange Administrator or Global Administrator privileges in the Microsoft 365 admin center before attempting to modify mailbox permissions or assign licenses.

Solution 1Recommended

Reconfigure Delegated Access Without a Password

Use this method to restore the standard shared mailbox behavior, allowing users to access it via their own accounts without needing a dedicated Exchange Online license.

A shared mailbox normally does not require a license unless it exceeds service limits or is accessed directly. Assigning a password implies direct sign-in, which triggers a license requirement. To fix this, you must rely entirely on delegated permissions.

Open the Microsoft 365 Admin Center

Navigate to Shared Mailboxes

Go to the left navigation menu, expand 'Teams & groups', and select 'Shared mailboxes'.

Select the Restored Mailbox

Locate and click on the restored shared mailbox from the list to open its properties pane on the right side of the screen.

Verify Delegated Permissions

Under the 'Read and manage' section, verify that the affected users are listed. If they are missing, click 'Edit' to add the users who need access to the mailbox.

Instruct Users to Access via Outlook

Advise users to access the shared mailbox directly from their primary Outlook client (it should appear automatically in their folder pane or can be added via 'Add shared folder') instead of signing in with the shared mailbox's credentials.

Reconfigure Delegated Access Without a Password

License Requirement Waived: As long as users access the mailbox via delegation and the mailbox storage remains under 50 GB, no additional Exchange Online license is required.

Solution 2

Assign a License for Direct Sign-In

If your organizational workflow strictly requires users to sign in directly to the shared mailbox using its own username and password, you must assign an Exchange license.

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Frequently Asked Questions

Why does my restored shared mailbox suddenly require an Exchange license?

If a password was assigned during the restoration process, the system treats it as a standard user mailbox configured for direct sign-in. Standard mailboxes that users log into directly always require an Exchange Online license to function.

How do users access a shared mailbox without a password?

Users should sign into Microsoft Outlook using their own primary Microsoft 365 credentials. Once an administrator grants them 'Read and manage' permissions, the shared mailbox will automatically map and appear in their folder pane.

Are there any storage limits on a shared mailbox before it needs a license?

Yes, an unlicensed shared mailbox accessed via delegated permissions is limited to 50 GB of storage. If the mailbox exceeds 50 GB or requires an In-Place Archive feature, you must assign an Exchange Online Plan 2 license.

Outlook & Email Problems