Unable to delete messages from shared mailbox

Question

All of the users of a shared mailbox are reporting they are unable to delete any messages.

The mailbox itself is 50% quota, I checked mailbox stats, it says Recoverable Items is 105GB, but it also says that "StorageQuota = unlimited"

Is the recoverable items full or not? I thought 100GB was the limit for a user mailbox with archive enabled, but this is a shared mailbox so I cannot enable archive.

How can I resolve this, I'm not clear if the recoverable items is full or not, but is it is, what are my options?. Every search on this says to enable auto-expanding archive, but how is this possible on a shared box?

Answer 1

The quotas for the Recoverable Items folder are automatically increased to 90 GB and 100 GB, respectively, when you place a mailbox on Litigation Hold or In-Place Hold or if a Microsoft 365 or Office 365 retention policy is applied to the mailbox.

Check this - https://learn.microsoft.com/en-us/exchange/security-and-compliance/recoverable-items-folder/recoverable-items-folder

To resolve this -

1. You can use PowerShell to clean up the folder. This involves removing items that are no longer needed, such as old versions of deleted items.

For example, you can use the following PowerShell command to clear items from the folder:

Search-Mailbox -Identity "Shared Mailbox Name" -SearchDumpsterOnly –DeleteContent

1. You can also lower the retention period if the mailbox has a long policy, such as keeping deleted items for 180 days. Reducing this will store less data in the Recoverable Items folder, helping to free up space.
2. Additionally, for important but infrequently accessed items, you can export them to a .pst file for long-term storage. After exporting, these items can be deleted from the mailbox to further reduce its size and improve performance.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Answer 2

The quotas for the Recoverable Items folder are automatically increased to 90 GB and 100 GB, respectively, when you place a mailbox on Litigation Hold or In-Place Hold or if a Microsoft 365 or Office 365 retention policy is applied to the mailbox.

Check this - https://learn.microsoft.com/en-us/exchange/security-and-compliance/recoverable-items-folder/recoverable-items-folder

To resolve this -

1. You can use PowerShell to clean up the folder. This involves removing items that are no longer needed, such as old versions of deleted items.

For example, you can use the following PowerShell command to clear items from the folder:

Search-Mailbox -Identity "Shared Mailbox Name" -SearchDumpsterOnly –DeleteContent

2. You can also lower the retention period if the mailbox has a long policy, such as keeping deleted items for 180 days. Reducing this will store less data in the Recoverable Items folder, helping to free up space.
3. Additionally, for important but infrequently accessed items, you can export them to a .pst file for long-term storage. After exporting, these items can be deleted from the mailbox to further reduce its size and improve performance.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Answer 3

Hello, @Geezer32,

Welcome to the Microsoft Q&A platform!

Based on your description, you are faced of a situation where the users are unable to delete any messages in a shared mailbox.

Despite the “StorageQuota = unlimited” for the mailbox overall, the Recoverable Items folder in a shared mailbox is hitting the internal soft limit (around 100GB) that Microsoft uses to protect performance and prevent runaway storage. That is why users are now reporting that they can’t “delete” messages—because the deleted items (and their later hard-deletion attempt into the Recoverable Items folder) have nowhere to go.

For you cannot enable an auto-expanding archive on a shared mailbox, you’ll need to manage (reduce) the size of the Recoverable Items folder. Options include:

1. Assess which items in the Recoverable Items folder can be safely purged.
2. Use the Exchange Online PowerShell (or the Microsoft 365 compliance portal) commands to search for and remove older items from the Recoverable Items folder.
3. Monitor the folder’s size after cleanup and consider using retention policies to ensure that items older than a certain age are automatically removed.
4. If there are no operational policies preventing you from converting the shared mailbox to a fully licensed mailbox, that may allow auto-expanding archive, which removes the manual cleanup overhead.

Should you need more help on this, you can feel free to post back. 

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If the answer is helpful, please click on “Accept answer” as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

Thank you for your support and understanding.

Best Wishes,

Alex Zhang