"Mailbox is full" warning even if the mailbox hasn't reached the storage limit

Article
06/24/2024
Applies to:

Exchange Online

Symptoms

A user experiences one of the following symptoms.

Symptom 1

The user receives a "mailbox is full" warning message for a mailbox that hasn't reached the storage limit.

Symptom 2

When the user deletes email messages, the following warning message is displayed:

The operation could not be completed.

Symptom 3

The user can't change or accept a calendar invitation.

Cause

This issue occurs if the mailbox size exceeds the mailbox quota. The mailbox size that the user sees isn't the actual size because it doesn't include the Recoverable Items folder. This folder isn't visible to users.

Resolution

Here's how to resolve this issue:

Verify the storage quotas of the user's mailbox by running the following cmdlet:
```
Get-Mailbox user@contoso.com | fl ProhibitSendReceiveQuota,RecoverableItemsQuota
```
Then, verify the status of the mailbox quota by running this cmdlet:
```
Get-MailboxStatistics user@contoso.com | fl StorageLimitStatus,TotalItemSize,TotalDeletedItemSize
```
- If the StorageLimitStatus value isn't blank, this means that the mailbox size exceeds the quota. The user will encounter the issue that's mentioned in the "Symptoms" section.
- The TotalItemSize value refers to the portion of the mailbox that's visible to the user. The TotalDeletedItemSize value refers to the size of the Recoverable Items folder that isn't visible to the user.
If the TotalItemSize value exceeds the ProhibitSendReceiveQuota value, or if the TotalDeletedItemSize value exceeds the RecoverableItemsQuota value:
- For Symptoms 1 and 3, you can either ask the affected user to delete items from the mailbox, or you can follow the next steps.
- For Symptom 2, follow the next steps.

Here are the steps to fix this issue:

Verify that an archive is enabled for the affected user's mailbox by running the following cmdlet:
```
Get-Mailbox user@contoso.com | fl ArchiveStat*
```
If the ArchiveStatus value is Archive, and if the ArchiveState value is Local, an archive is enabled in the cloud service. In this case, go to step 3.

If no archive is enabled, check whether the user is on hold by running the following cmdlet:
```
Get-Mailbox user@contoso.com | fl *HoldEnabled
```
If at least one of the returned values is True, this means that the user is on hold. If you don't want to enable an archive for that user, you must remove messages from the Recoverable Items folder. To learn more about the Recoverable Items folder, the storage quota, and how the folder interacts with In-Place Hold and Litigation Hold, see Recoverable Items folder in Exchange Online.
Enable an archive, and set up a retention or deletion policy to automatically process email messages. To learn more, see Set up an archive and deletion policy for mailboxes in your organization.
Verify which retention policy is applied to the affected user by running the following cmdlet:
```
Get-Mailbox user@contoso.com | fl RetentionPolicy
```
Be aware that such policies automatically archive or delete items from the mailbox after some time.
If a retention policy was recently modified or applied to the affected user, run mailbox processing manually by using the following cmdlet:
```
Start-ManagedFolderAssistant user@contoso.com
```
This cmdlet starts the mailbox processing tasks that run retention policies and clear messages as configured. Wait at least one hour, and then check the mailbox again.

If these steps don't resolve the issue, contact Microsoft Support for assistance.

More information

For information about other issues that might prevent retention policies from deleting email messages, see Resolve email archive and deletion issues when using retention policies.

Still need help? Go to Microsoft Community.

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