Learn about auto-expanding archive - Microsoft Purview (Compliance) (2023)

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Archive mailboxes in Microsoft Purview provide users with additional mailbox storage space. Once a user's archive mailbox is activated, up to 100 GB of additional storage is available.

This archiving feature in Microsoft Purview (calledauto-expanding file) provides up to 1.5 TB of additional storage space in archive mailboxes. When the archive mailbox storage quota is reached, Microsoft Purview automatically (and incrementally) increases the archive size until the archive mailbox reaches 1.5 TB.

For step-by-step instructions on how to enable auto-expanding archiving, seeEnable auto-expand file.

This is how the auto expand file works

As explained in the introduction, additional mailbox space is created when a user's archive mailbox is activated. When auto-expanding archiving is enabled, Microsoft Purview periodically checks the size of the archive mailbox. When an archive mailbox reaches its storage limit, additional storage space is automatically created for the archive. When the user runs out of extra space, more space is automatically added to the user's file. This process continues until the user file reaches a size of 1.5 TB. This process is automatic, which means that administrators do not need to request additional file storage or manage auto-expanding files.

Here is a brief description of the process.

1. Archiving is enabled for a user mailbox or a shared mailbox. An archive mailbox with 100 GB of storage space is created, and the archive mailbox warning quota is set to 90 GB.

2. An administrator enables auto-expanding archiving for the mailbox. If the mailbox has a hold or lock policy applied, the archive mailbox storage quota increases to 110 GB and the archive alert quota increases to 100 GB.

   Then, when the archive mailbox (including the Recoverable Items folder) reaches its storage quota, the archive mailbox is converted to an auto-expanding archive. Additional storage is added up to a maximum size of 1.5TB. It may take up to 30 days for additional storage to be provided.

3. Microsoft Purview automatically adds more storage space as needed.

What moves to additional file space?

Folders can be moved to make efficient use of automatically expanding file memory. Microsoft Purview determines which folders are moved when additional space is added to the file. Sometimes moving a folder automatically creates one or more subfolders and distributes items from the original folder to those folders to simplify the move process. It may be necessary to communicate this behavior to end users after enabling their mailboxes so that the files automatically expand to meet expectations.

When you view the file portion of the folder list in Outlook, these subfolders appear below the original folder. The naming convention that Microsoft 365 uses to name these subfolders is<folder name>_yyyy (Created on dd mmm, yyyy h_mm), Wo:

• aaaaaais the year that the messages in the folder were received.

• mmm tt, aaaa h_mis the date and time the Office 365 subfolder was created, in UTC format, based on the user's time zone and regional settings in Outlook.

The screenshots below show a list of folders before and after messages are moved to an auto-expanding file.

Before adding additional memory

After adding additional memory

Outlook requirements to access items in an auto-expanding file

To access messages stored in an auto-expanding file, users must use one of the following Outlook clients:

• Outlook as part of Microsoft 365 Apps for enterprise (formerly known as Office 365 ProPlus)

• Outlook as part of Microsoft 365 Apps for enterprise (formerly called Office 365 Business)

• Outlook 2016 or Outlook 2019 for Windows

• Outlook on the web when the primary mailbox is in Exchange Online instead of on-premises

• Outlook 2016 or Outlook 2019 for Mac

Here are some things to consider before enabling an auto-expanding mailbox:

• Users can access all folders in their archive mailbox, including those that have been moved to the auto-expanding storage area.

• If an archive mailbox has at least one auto-expanded extension, users cannot delete an archive mailbox or auxiliary file folder. In other words, you can no longer exclude folders from the archive after provisioning an auto-expanding storage area.

• Users can delete items in an auto-expanding storage area. However, you cannot use them.Function to recover deleted itemsto retrieve an item after auto-expanding archiving has been enabled for your mailbox.

  (Video) How to use In Place Archive | Microsoft 365 Online Archive

• Advanced automatic file search is available in Outlook for the web (OWA). Similar to the online archive, users can search for objects that have been moved to an additional storage area. When File is selected as the search scope in OWA, all files (including self-expanding files) and their corresponding subfolders are searched.

• Automatic file search is available if you're using Outlook for Windows on the monthly retail channel, version 16.0.13519+. With this update, the current mailbox panel is available, allowing users to automatically search the improved archive. However, the search is not recursive for nested subfolders within each file folder.

• Search does not support the auto-expanding archive feature in a cloud-only archive scenario (the primary mailbox is still on-premises). For more information about this and other Microsoft Search support resources, seeHow Outlook for Windows connected to Exchange Online uses Microsoft Search.

• The number of items in Outlook and the number of read/unread items (in Outlook and Outlook on the web) in an auto-expanding file may not be accurate.

File auto-expanding and other compliance features

This section explains the functionality between auto-expanding archiving and other compliance features.

• electronic discovery:When you use an eDiscovery tool such as content search, it also looks for additional storage areas in an auto-expanding file.

• retention:When you archive a mailbox using methods such as Microsoft 365 Hold, eDiscovery case hold, and Litigation Hold in Exchange Online, the content is also archived in an auto-expanding archive.

• Message recording management (MRM):If you use MRM deletion policies in Exchange Online to permanently delete expired mailbox items, any expired items that are in the auto-expand file are also deleted.

Next steps

For more technical details on the auto-expand file, seeMicrosoft 365: Automatic file expansion FAQ.

If you're ready to enable auto-expanding archiving, keep readingEnable auto-expand file.