full archive mailbox?

Question

I get continuous emails stating my archive mailbox is full but i have emptied it. How do i empty a full archive mailbox?

Answer 1

Hi @Judith Trotman (Sydney LHD),

Good day. I hope you are doing well.

Based on what you’ve shared, it appears that you are continuing to receive archive mailbox full notifications even after clearing content from the Online Archive. After some research, here are a few suggestions that may help.

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1/ Check in Classic Outlook (Online Archive cleanup)

If you are using Classic Outlook on Windows, please note that deleting emails from the Online Archive will not free up space until the Deleted Items folder inside the Online Archive is also emptied.

You may wish to expand your Online Archive, locate Deleted Items under the archive, and empty that folder to ensure the space is released.

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2/ Ask your administrator to verify the archive status

If you continue to receive archive mailbox full notifications after completing the above, please ask your Microsoft 365 administrator to review your Online Archive in the Exchange admin center.

Here are the steps you can share with them:

• Sign in to the Exchange admin center.
• Go to Recipients > Mailboxes, select the affected mailbox, then open Others > Manage mailbox archive.

• Under Mailbox archive status, confirm that the Online Archive is enabled and review the Archive usage, which shows the current usage and storage limit.

• If the archive mailbox has reached its storage limit, the administrator can verify whether your account is assigned a license that supports auto‑expanding archiving (such as Exchange Online Plan 2 or Microsoft 365 E3/E5) and follow Microsoft’s official guidance to enable auto‑expanding archiving if needed. For reference: Enable auto-expanding archiving | Microsoft Learn.
• If your IT administrator confirms that the Online Archive is not full, they can try to address the issue by following Microsoft’s guidance: (Mailbox is full) warning when it hasn't reached quota - Microsoft 365 | Microsoft Learn to review mailbox and archive quotas, confirm that an archive is correctly enabled, and ensure retention or cleanup processes are running as expected.

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3/ Contact Microsoft support

Should the issue persist after performing the above, your administrator may need to engage Microsoft Support for further investigation. A technical support engineer can then initiate a remote session, review backend settings, and run diagnostics. If needed, they can escalate the case to specialized engineering teams who are well-equipped to perform advanced troubleshooting and provide targeted solutions.

As moderators, our primary goal is to provide helpful guidance and support through general troubleshooting steps. While we don’t have access to internal systems or administrative tools required to resolve account-specific or backend issues, we truly appreciate your understanding of these limitations. We genuinely hope the information we share helps point you in the right direction, and we're always here to assist as much as we can within our scope.

For guidance on how to request support in the admin center, please share the following resource to the IT admin: Get support - Microsoft 365 admin. 

I hope this information is useful. Thank you for taking the time to raise this question. If you need any further clarification or assistance, please feel free to leave a comment under this post.

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Thank you for your contributions to the forum.

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Answer 2

For a business mailbox in Classic Outlook, the “archive mailbox is full” warning usually means the overall mailbox or the hidden Recoverable Items area is still over quota, even if visible Archive folders look empty.

Use these steps to confirm and fix it (admin/PowerShell required):

1. Check mailbox and archive quotas Run in Exchange Online PowerShell:

      Get-Mailbox ******@contoso.com | fl ProhibitSendReceiveQuota,RecoverableItemsQuota
      Get-MailboxStatistics ******@contoso.com | fl StorageLimitStatus,TotalItemSize,TotalDeletedItemSize
   

   • If StorageLimitStatus is not blank, the mailbox is over a quota.
   • TotalItemSize = visible mailbox (including Archive that counts toward the mailbox).
   • TotalDeletedItemSize = Recoverable Items (dumpster), not visible in Outlook but still counted.
2. If over quota
   • If TotalItemSize > ProhibitSendReceiveQuota, more content must be removed from the primary/archive folders (or the quota increased by the admin).
   • If TotalDeletedItemSize > RecoverableItemsQuota, the Recoverable Items folder is full and must be reduced (for example, by adjusting retention/hold or letting retention policies purge items).
3. Confirm that an Online Archive is actually enabled Run:

      Get-Mailbox ******@contoso.com | fl ArchiveStat*
   

   • If ArchiveStatus = Archive and ArchiveState = Local, an archive is enabled in the cloud service.
   • If no archive is enabled, the warning is about the primary mailbox/Recoverable Items, not a separate online archive.
4. Clean up from Outlook (user side) Even after emptying the visible Archive folder, other folders may still be large:
   • Use File > Tools > Mailbox Cleanup in Classic Outlook to:
     • View mailbox size and identify large folders (including Archive).
     • Find and delete old or large items.
     • Empty Deleted Items so those messages are removed from the quota.
   • Delete items from Archive and then empty Deleted Items again; items only stop counting after they are removed from Deleted Items.
5. If still getting “full” messages after cleanup
   • It can take some time for quota status to update across services.
   • If PowerShell still shows StorageLimitStatus not blank or TotalDeletedItemSize over RecoverableItemsQuota, an Exchange admin must:
     • Increase quotas where appropriate, or
     • Adjust retention/hold settings so Recoverable Items can be purged.

If the archive is a local .pst file (personal archive) rather than an Exchange Online Archive, deleting items and then emptying Deleted Items in that .pst is what actually frees space in that file.

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References:

• "Mailbox is full" warning even if the mailbox hasn't reached the storage limit
• Manage my mailbox size in Outlook
• Mailbox storage limits in Outlook
• How to delete Archived messages? - Microsoft Q&A

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