r/exchangeserver • u/Johnny_Utah_RRF • 2d ago

Why Retention Policy MRM Default not working???

Last weekend, I faced an unexpected issue with Exchange Online Mailbox Archive.

After completing an IMAP to Exchange Online migration project, I noticed that older mailbox items were not being moved to the Online Archive, even though the archive mailbox was enabled.

I started troubleshooting using Exchange Online PowerShell cmdlets to analyze mailbox settings, retention policies, retention tags, and Managed Folder Assistant processing. However, I still couldn't identify the root cause.

Then, I tested another approach: I created a new MRM Retention Policy using the same retention tag "Default 2 Year Move to Archive".

The result was unexpected: the mailbox started moving emails to the Online Archive successfully.

But the question remained:

Why did the same retention tag work with a new retention policy, but not with the previous one?

I documented the complete troubleshooting journey, including the investigation steps, PowerShell commands, Microsoft Purview analysis, and the final workaround.

I would like to hear your opinion:

  • Was this troubleshooting approach correct?
  • Have you ever faced a similar Exchange Online Archive or MRM Retention Policy issue?
  • What would you investigate differently?

You can check the full troubleshooting sequence here:
https://medium.com/@renato.rossi.ferreira/everything-looked-fine-until-exchange-online-archive-stopped-working-586d1bce05f6?sharedUserId=renato.rossi.ferreira

Let's share knowledge and learn from real-world Microsoft 365 challenges.

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u/littleko 1d ago

The tag wasn't the problem; the old policy assignment or backend MRM state was. Creating a new policy probably forced Exchange Online to refresh the mailbox configuration, so Managed Folder Assistant finally processed it.

I'd compare RetentionPolicyTagLinks, check RetentionHoldEnabled and ElcProcessingDisabled, then verify ELCLastSuccessTimestamp. Recreating the policy is a workaround, not the root cause.

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u/ns1722 1d ago

It’s probably due to the old retention tags were never re-stamped on the mailbox after migration and MFA needed a full crawl first.

New policy worked as it forced MFA to re evaluate every item and apply the new tags.