Retention Policies to Archive and Delete mail

Question

Scenario:

Microsoft 365 Tenant. User has a 365 Business Premium license. Online Archive Mailbox is enabled. The user's Online Archive is out of space (it is at 90% utilization). The user does not want to add an Exchange Online Plan 2 license to increase Archive storage. The user has requested that anything in the archive older than 2 years can be deleted.

Configuration:

Using the Exchange (Legacy) MRM I have retained the default Tag to move anything older than 2 years from the Mailbox to the Archive. I have created a new Tag to delete anything older than 4 years and applied it to the entire mailbox.

Using the Exchange (Legacy) MRM I have created a new Retention Policy for the user. The policy consists of both the Archive after 2 years and Delete after 4 years Retention Tags.

The new Retention Policy has been applied to the user's mailbox.

Using the Exchange Online PowerShell, I have manually executed the Folder Manager against the user's mailbox.

Understanding:

My understanding of the above is, as follows:

• Any email in the Primary Mailbox that is older than 2 years will be automatically moved to the user's Online Archive
• Any email in the Online Archive that is older than 4 years will be automatically deleted from the archive
• This will mean that for the first 2 years, email will remain in the Primary mailbox. Once the message reaches 2 years in age, it will be moved to the Online Archive. The Online Archive will retain messages for an additional 2 years (per the user's request). Once the message reaches 4 years (in total age), it is deleted from the Online Archive.

Problem:

This is not working. Email has been moving from the Primary to the Online Archive, but it does not appear that messages are being deleted from the Online Archive, as the utilization is still at 90%.

Question:

What is wrong with the configuration that it is not working as expected?

Answer 1

Hi,

I had kind of the same issue with Online Archive not clearing up as expected, even with correct tags. Sometimes the deletion tag just don’t run properly, even after applying the retention policy and forcing it with PowerShell.

Make sure that Managed Folder Assistant has really run recently on the archive. Try this: Start-ManagedFolderAssistant -Identity ******@domain.com

Then wait a bit (can take few hours) and recheck. Also double check that the Retention tag to delete after 4 years is really of type “Personal” and not “Default” or “All” – had that mistake once and it didn’t delete anything.

Hope that helps.

— Nicolas

Answer 2

Your understanding is correct, there are small caveats depending on the item type, but in general it should work exactly as you expect. Keep in mind however that the background process responsible for retention processing runs on a weekly schedule in Exchange Online, which means it can take a while to process the mailbox, especially after changes in the assigned retention policy. The Start-ManagedFolderAssistant cmdlet only "signals" the background process to act as soon as possible, but doesn't necessarily mean that processing will happen immediately. And in the scenario of reassigning retention policy/tags, it's best to run it with the -FullCrawl switch parameter.

Apart from that, just give it some time. If needed, you can always manually delete some items in the Online archive to free up space until retention kicks in.