Online Archive retention policy with a 3-month retention tag to the mailbox

Verify that the 90-day tag is an enabled Default Policy Tag (Type: All) with MoveToArchive, confirm it is linked to the mailbox’s assigned policy, and then queue the mailbox for Managed Folder Assistant processing.

1. Validate the archive tag and assigned policy

Run these commands in Exchange Online PowerShell, replacing the example mailbox and policy/tag names:

Get-Mailbox [Email] |
    Format-List ArchiveStatus,RetentionPolicy,RetentionHoldEnabled,ElcProcessingDisabled

Get-RetentionPolicy "PolicyName" |
    Select-Object -ExpandProperty RetentionPolicyTagLinks

Get-RetentionPolicyTag "TagName" |
    Format-List Name,Type,RetentionEnabled,AgeLimitForRetention,RetentionAction

The expected configuration is:

• ArchiveStatus: the archive mailbox is enabled.
• The intended retention policy is assigned.
• The 90-day tag appears in RetentionPolicyTagLinks.
• RetentionEnabled: True.
• AgeLimitForRetention: 90.00:00:00.
• RetentionAction: MoveToArchive.
• Type: All for an automatic mailbox-wide archive tag.

MoveToArchive is supported for default policy tags and personal tags, not retention policy tags assigned automatically to default folders. A personal tag only processes folders or items to which the user has applied it; use a Type: All default policy tag when every otherwise-untagged item should move automatically.^1^

2. Queue mailbox processing

If the configuration is correct, run:

Start-ManagedFolderAssistant -Identity [Email]

The command triggers processing but does not guarantee that messages move immediately. Exchange Online processes mailboxes at least once every seven days, so eligible items can remain in the primary mailbox for up to seven days.^2^

Retention age for ordinary email is generally calculated from its delivery or creation date—not simply from where the message currently appears. Deleted Items, recurring calendar entries, tasks, contacts, and corrupted items have different processing rules.^3^

3. Check mailbox-level blockers

From the first command’s output:

• If RetentionHoldEnabled is True, remove the retention hold if organizational requirements permit it.
• If ElcProcessingDisabled is True, enable MRM processing:

Set-Mailbox [Email] -ElcProcessingDisabled $false
Start-ManagedFolderAssistant -Identity [Email]

Also account for these documented conditions:

• MRM does not process mailboxes smaller than 10 MB automatically. For such a mailbox, run Start-ManagedFolderAssistant whenever processing is required.
• A disabled user account associated with a regular mailbox is not processed; this limitation does not apply to shared mailboxes.
• Very large mailboxes or mailboxes containing many items can process more slowly.^2^ ^4^

4. Check whether another tag overrides the 90-day tag

Export folder statistics:

Get-MailboxFolderStatistics [Email] `
  -IncludeOldestAndNewestItems |
  Export-Csv .\primaryfolderstats.csv -NoTypeInformation

Review these columns:

• OldestItemReceivedDate
• ArchivePolicy
• DeletePolicy
• CompliancePolicy
• RetentionFlags

An explicitly assigned personal tag takes precedence over folder-level and default tags. A disabled tag or a Never Move to Archive personal tag can therefore prevent selected folders or messages from following the 90-day default policy.^1^

5. Collect diagnostics if processing still fails

After allowing the processing window, export the MRM diagnostic log:

Export-MailboxDiagnosticLogs [Email] -ComponentName MRM

Review it for the last processing time and processing errors. If the policy was recently changed and mailbox data indicates that the expected tag is missing from the mailbox’s MRM configuration, run a full crawl:

Start-ManagedFolderAssistant -Identity [Email] -FullCrawl

If eligible messages still remain after seven days, provide Microsoft Support with the mailbox properties, tag and policy output, folder statistics, and MRM diagnostic log.^2^

References

1. Retention tags and retention policies in Exchange Online
2. Resolve email archive and deletion issues when using retention policies
3. How retention age is calculated in Exchange Online
4. Messages aren't moved to archive mailboxes after you create a retention policy in Exchange Online