Deleted Items never delete

Question

I have a mailbox where Deleted Items never delete or move to Recoverable Items, even after one year. I have confirmed there is no Litigation Hold. I have tried removing all Retention Policies, applying only the Default Retention Policy, and adding a specific Deleted Items tag set to permanently delete items after one month to the Default Retention Policy. The Microsoft Purview Policy Lookup shows no active Retention Policies. I have also tried renaming the mailbox and creating a new mailbox, and the new mailbox has the same symptoms.

Are there any other places I might check to figure out why my Deleted Items never delete?

Cheers,

Answer 1

The issue has finally been resolved. Apparently, somehow the SingleItemRecoveryEnabled flag was set to TRUE on the mailbox. Once set to FALSE and starting the Mailbox Folder Assistant, I was able to begin deleting items from the Deleted Items folder, thus reducing the mailbox storage size. If anyone else has this issue going forward, here are the commands used to identify the flag and set it to false, effectively solving the problem.

I hope this helps someone! Good luck out there!

Answer 2

Hi @Jason 

Thanks for reaching out to the Microsoft Q&A forum.  

Based on my research, the default MRM retention policy does not include a Deleted Items tag. In my testing, the tag does not remain saved after being added to the default MRM retention policy. I attempted this both through PowerShell and through Microsoft Purview, and the behavior was the same. This explains why, even though you assigned a Deleted Items tag to the default MRM policy, it still does not apply correctly, including for newly created mailboxes. 

Furthermore, the Deleted Items tag is a retention policy tag that applies only to the default folders. It does not automatically apply across the entire mailbox. 

With that in mind, I recommend creating a custom retention tag that deletes email after the period you prefer. When creating this tag, please remember to select “Automatically to entire mailbox (default)” so the tag can apply to all items throughout the mailbox. 

After creating the tag, you can add it to your default MRM retention policy. 

Once the policy is updated, you can manually trigger processing by running the following PowerShell command: 

Start-ManagedFolderAssistant –Identity UPN 

References: 

• Default Retention Policy in Exchange Online | Microsoft Learn 
• Create a Retention Policy in Exchange Online | Microsoft Learn 
• Start-ManagedFolderAssistant (ExchangePowerShell) | Microsoft Learn 

I hope this helps clarify the situation and guides you toward the next steps. 

If you have any updates or additional questions, please feel free to reach out. 

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