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Messaging Records Management (MRM) for Mailboxes in Office 365

Updated: May 9

Messaging Records Management, or MRM, is a feature of Exchange Online that allows administrators to manage the email lifecycle of their organization and implement effective retention strategies.

MRM in Exchange Online is configured using retention tags and policies in the Classic Exchange Admin Center.

How MRM works

Retention tags and retention policies

MRM in Exchange Online works using retention tags and retention policies. Administrators can group retention tags into a retention policy and then apply the policy to a user’s mailbox.

Retention tags are used to apply retention settings to folders and individual items. These settings define the period a message remains in a mailbox and the action to be taken after the message reaches the specified retention age. When a message reaches its retention age, it is deleted or moved to the user's archive.

Retention tags can be linked to or unlinked from a retention policy at any time, and the changes automatically take effect for all mailboxes that have the policy applied.

Note: You can only apply one retention policy to a mailbox.

retention policy mailbox 365

There are three different types of retention tags available: Default Policy Tag, Retention Policy Tag, and Personal Tag.

How MRM Works

Actions involved when you deploy MRM

When creating retention tags, there are three actions you can choose from that will take place when the retention period is over. The actions are:

Delete and allow recovery :

This is similar to what happens when a user empties the Deleted Items folder. The items move to the Recoverable Items folder and stay there till the retention period has passed.

Move items to an archive automatically :

This moves the message to the user’s archive mailbox after reaching the retention age. However, no action will be taken if the archive mailbox is not enabled. This action is only available for Default Policy Tags and Personal Tags.

Permanently delete :

If you choose this action, the message will be permanently deleted after the retention period. The only way this data can be found again is if it is placed on litigation hold.

How to deploy MRM?

There are three steps you need to follow to deploy MRM:

How to deploy mrm

Managed Folder Assistant

In MRM, the Managed Folder Assistant (MFA) is a throttle-based assistant responsible for processing the policies applied to the user mailboxes. In other words, the MFA inspects the mailbox items for retention policies, and when a policy is detected, it stamps the item with appropriate retention tags. It then takes the specified retention action on items once they are past their retention age.

The MFA does not need to be scheduled or maintained; it is permanently active. Another thing to note is that at a specified interval (known as the work cycle checkpoint), the MFA refreshes the list of mailboxes to be processed. During the refresh, the MFA checks for newly created or moved mailboxes and subsequently adds them to the queue. It also inspects mailboxes that haven’t been processed due to failures and adds them higher in the priority queue.

What retention policy has priority?

What happens when multiple retention tags are applied to a single mailbox item? Microsoft has clearly outlined the priority of the MRM tags to determine which action will be implemented.

When an item is tagged manually using a Personal Tag (PT), it takes the highest priority.

Next, the Retention Policy Tag (RPT) is executed, where the item sits in the folder where the tag is applied.

Finally, general mailbox policies through a Default Policy Tag will be applied if none of the other two methods has been used to implement the retention policy.

what retention policy has priority

Default MRM policy

The Default MRM policy is automatically applied when a new mailbox is created in Exchange Online. You can change the retention policy applied to a user at any point in time.

Tags included in the Default MRM Policy can be modified according to your business needs. You can change the retention age or retention actions, turn off a tag, or modify the policy by adding or removing tags from it. The updated policy is applied to mailboxes the next time they are processed by the MFA.

The Default MRM Policy contains the following retention tags

● 1 Month Delete

● 1 Week Delete

● 1 Year Delete

● 5 Year Delete

● 6 Month Delete

● Default 2 year move to archive

● Junk Email

● Never Delete

● Personal 1-year move to archive

● Personal 5-year move to archive full-time

● Personal never move to archive

● Recoverable Items 14 days move to archive

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