Learn about archive mailboxes


Microsoft 365 compliance is now called Microsoft Purview and the solutions within the compliance area have been rebranded. For more information about Microsoft Purview, see the blog announcement and the What is Microsoft Purview? article.

Mailbox archiving in Microsoft 365 (also called In-Place Archiving) provides users with additional mailbox storage space. After you turn on archive mailboxes, a user's current mailbox becomes their primary mailbox and an additional mailbox is created, called the archive mailbox. Both mailboxes are considered a user's mailbox for compliance features such as Content search from the Microsoft Purview compliance portal, Microsoft 365 retention, and Litigation Hold.

Users can access and store messages in their archive mailboxes by using Outlook and Outlook on the web. Users can also move or copy messages between their primary mailbox and their archive mailbox. They can also recover deleted items from the Recoverable Items folder in their archive mailbox by using the Recover Deleted Items tool.

Managing archive mailboxes with Messaging Records Management (MRM)

Messages can also be moved to the archive mailbox by the default Exchange retention policy from Messaging Records Management (MRM). This default policy is automatically assigned to every mailbox and does the following:

  • Moves items that are two years or older from a user's primary mailbox to their archive mailbox.

  • Moves items that are 14 days or older from the Recoverable Items folder in the user's primary mailbox to the Recoverable Items folder in their archive mailbox.

You can customize your organization's MRM policy with retention tags. For an example configuration, see Set up an archive and deletion policy for mailboxes in your organization.


MRM, like Microsoft 365 retention policies and retention labels, can also automatically delete emails after a specified period. As an older technology than Microsoft 365 retention, MRM continues to work side-by-side with retention policies and retention labels from Microsoft Purview. For more information, see Use retention policies and retention labels instead of older features.

Auto-expanding archiving

After a user's archive mailbox is enabled, up to 100 GB of additional storage is available. If users need more storage space, enable auto-expanding archiving to provide up to 1.5 TB of additional storage in archive mailboxes. For more information, see Learn about auto-expanding archiving.


For a list of Outlook licenses that support archive mailboxes, see the references to In-Place Archiving in Outlook license requirements for Exchange features.

Next steps

See Enable archive mailboxes in the Microsoft Purview compliance portal.