Being an Office 365 admin is a role of many responsibilities as they oversee handling other user’s data. The heavy task of deletion, retention and archiving of data also relies on their shoulders. However, it can be simplified by customizing the policies according to the needs of their organization. Admins can create a few archiving and deletion policies known as MRM (Messaging Retention Management) which are applied on the user’s mailbox and capable of automatically moving email messages from the primary mailbox to the archive folder and eventually delete them once its purpose is served. A retention tag is also assigned to a particular folder or message and that decides the entire lifecycle of that message, from the time it will stay in the primary mailbox to its deletion or transfer to archive mailbox after its retention age has expired. In here, the administrator must mention all the details of the items which are to be moved.

Tasks that the administrator needs to perform for policy creation are:

  1. Enable user’s archive mailbox

    Enable the archive mailbox for each user in the organization so that the retention tag will find it easier to move the objects in it. Also, the user can also archive information manually. It allows more storage space for the user’s data.

  2. Create retention tags as per the criteria
    • Move the messages which are older than 3 years from the primary mailbox to the archive mailbox. It will give you some free space in the primary one.
    • Delete the 5-year older messages from the deleted items folder permanently. This will free up some storage space and in fact these messages can be recovered at any given time.
    • Permanently delete the 7-year older messages from both archive and deleted items folder. Sometimes, businesses must follow the compliance regulations, but most of the time, 7 years is enough period to delete the messages permanently.
  3. Create custom retention policy

    Create user-defined retention tags to handle the content. These are custom tags that a user assigns to a specific message of the mailbox.

Steps To Setup Archive And Deletion Policy For Office 365 Mailboxes

Setting up of MRM policy and Retention tag is a detailed process. But before we proceed to that, these are certain pre-requirements which are to be kept in mind-

  • Only a global admin can perform these procedures.
  • A default MRM policy is already in existence. The admin replaces it with the new one. Only one policy can be applicable at one time. Now, these are the steps which you need to conduct-
    1. Enable Users’ Archive Mailboxes
    2. Create new Retention tags for Archive & Deletion
    3. Create a new Retention Policy
    4. Assign new Policy to User Mailboxes
Step 1: Enabling Archive Mailboxes for Users

Items in the user's mailbox that are older than the archiving policy given to the mailbox will move to the new archive mailbox once the archive mailbox is active. Two years after the date an item was sent to or generated by a user in an Exchange Online mailbox, it is moved to the archive mailbox by default as part of the retention policy applied to such mailboxes.

To begin with, ensure each user has an enabled archive mailbox so that the messages with the retention tag ‘Move to archive’ can perform the task uninterruptedly. These are the steps to follow:

  1. In Microsoft 365 Admin Center, go to Exchange Admin Center and click on it to open. Go to Exchange Admin Center
  2. In the Recipients category, select Mailboxes and from the available Mailboxes, choose a mailbox in which you want to enable Archive mailbox. Single-click on it. Choose a mailbox in which you want to enable Archive mailbox
  3. Go to others section and open the Manage Archive Mailbox option. Open the Manage Archive Mailbox option
  4. Move the toggle from Off to On and Save the changes. Save the changes
Step 2: Creating Retention Tags for Archive and Deletion Policies

We are going to create three types of retention tags for the new retention (Archive and Deletion) policy in this step. Let us assign a common name (as per your choice) for these retention tags. Here, we are using Kernel.

  • Kernel 3 year Move to Archive (Custom Archive Policy)
  • Kernel 7 year Permanently Delete (Custom Deletion Policy)
  • Kernel Deleted Items and Allow Recovery 5 years (Custom tag for Deleted items folders)
Kernel 3 year Move to Archive (Custom Archive Policy)

This tag will automatically move items older than 3 years to Archive mailboxes. To create the custom tag, just follow the steps:

  1. In the Office 365 admin center, click Admin Centers < Exchange.
  2. In the Exchange Admin Center, go to Compliance Management and click Retention Tags. Click the + button and select the first option applied automatically to entire mailbox (default).
  3. On the new tag applied automatically to entire mailbox (default) page, provide the required details like Name, Retention action – Move to Archive, Retention period – 1095 days (3 years) with Comment (optional). Click Save to save the entries.
Kernel 7 year Permanently Delete (Custom Deletion Policy)

This tag will permanently delete items after 7 years. To create a custom retention tag, perform the steps:

  1. In Exchange Admin Center > Compliance Management > Retention Tags, click the + button and select applied automatically to entire mailbox (default).
  2. It will open the page new tag applied automatically to entire mailbox (default). Here, provide Name, select Retention action as Permanently Delete. Enter Retention period as 2555 days (7 years). Then, click Save to save the settings for this Retention tag.
Kernel Deleted Items and Allow Recovery 5 years (Custom tag for Deleted items folders)

This tag will automatically delete folder items after 5 years. It also provides a recovery period in which the user can recover those items using the Recover Deleted Items feature.

  1. On the retention tags page, select applied automatically to a default folder option from the list now.
  2. A page named new tag automatically applied to a default folder will get open. Provide a Name, select Deleted items from the list, select Delete and Allow Recovery as Retention action, and enter 1824 days (5 years) as Retention period. Click Save to create this tag.
Step 3: Creation of the retention policy

When you create an account in Office 365, a Default MRM Policy is created. You have to create a new retention policy and replace it with the Default MRM policy. First you should know about retention policy then creating a new retention policy, the user has to assign the created retention tags to it. Let us see how to create the retention policy and add retention tags to it.

  1. Go to Exchange Admin Center > Compliance Management > Retention Policies. Click the + button.
  2. In the new retention policy page, enter a Name and then click the + (add) button under Retention tags.
  3. In select retention tags, select the three newly created retention tags. Along with them, select the following tags:
    • Junk Email
    • Never Delete
    • 1 Month Delete
    • 1 Year Delete
    • Personal 1 year move to archive
    • Recoverable items 14 days move to archive

    After the selection, click add option to add the tags. Click OK to save the Retention tags.

  4. On the Retention policies page, select your created retention policy and click Save. You can view the tags linked to it within the right pane.
Step 4: Assign new Retention Policy to User Mailboxes

This step requires assigning a new retention policy to the user mailboxes of the Office 365 account. Perform the steps below to do this:

  1. Navigate to Exchange Admin Center, select Recipients, and then click Mailboxes. Select the user mailboxes you want to assign the policy and on the right-side panel, click More options and click Update for Retention Policy.
  2. On the Bulk Assign Retention Policy page, select your created retention policy from the drop-down list and click Save.

Hence the new Retention Policy is assigned to all the selected user mailboxes. To confirm, go to the Mailboxes page, select the mailbox, and click Edit and then on the Mailbox features option where you can confirm the assigned retention policy.

We have seen how to set up an Archive and Deletion Policy for Office 365 mailboxes. It may take 7 days for new retention policies to be applied to user mailboxes in Office 365. However, you can force this using the cmdlet: Start-ManagedFolderAssistant in Exchange Online PowerShell cmdlet.

To do this, execute the following command.

  1. Open your Windows PowerShell on your local system (run it as administrator).
  2. After opening, run the following command.

    $UserCredential = Get-Credential

  3. Then a dialogue box named Windows PowerShell Credential Request gets opened. Type your Office 365 global admin account username and password and then click OK.
  4. Execute the following command:

    Session = New-PSSession –ConfigurationName Microsoft.Exchange –ConnectionUri -Credential $UserCredential –Authentication Basic -AllowRedirection

    Then, run this command:

    Import-PSSession $Session

    To verify Exchange Online connection, run this command to get all mailboxes from your specified Office 365 account:


    Now run:

    Get-mailbox -resultsize unlimited

    Finally, run this command to complete the process:

    $Mailboxes.Identity | Start-ManagedFolderAssistant

Users are provided with a detailed manual procedure for assigning Archive and Deletion Policy for Office 365 mailboxes. It may take 7 days for the policy to come into effect. However, you can implement it forcefully (by starting Managed Folder Assistant using Windows PowerShell cmdlets) to apply retention policy immediately to the Office 365 mailboxes.

Backup Office 365 Using Professional tools

Archiving and retention features of Office 365 are mainly for specific items. You shouldn’t be solely dependent on them since they are not suitable for the backup of the entire Office 365 data. However, many professional tools allow complete and accurate Office 365 backup, including mailboxes, public folders, and archive mailboxes and saves them into the user’s preferred output format. It acts as a precautionary step which must be taken for the security of all your essential data. Also, it supports the all Office 365 backup plans.


Custom archive and deletion policies in Office 365 helps in the better management of data especially since it is specific to your own organization. These policies can be created by a global administrator and applied using the Exchange admin center and Exchange Management Shell. It is a lengthy procedure which involves a lot of steps but for your ease, all those have been discussed in detail above. However, if you need a comprehensive backup of Office 365 data, you need professional Office 365 Backup and Restore tool.