This article will help you set up an auto-expanding archive or unlimited archive on Office 365 mailboxes. More importantly, we will discuss the key features of archiving that will help you decide how and why you need to enable auto-expanding archives for your users.

Office 365 provides additional storage space with Archive mailboxes. By default, an archive mailbox can reach 100 GB size. The users start getting warnings as soon as 90GB is reached.

When you enable unlimited archiving, and the initial storage quota in a user's archive mailbox is reached, Office 365 automatically adds more storage space. This means that users will not run out of mailbox storage space, and the admin will not need to manage it after enabling the archive mailbox and the auto-expanding archiving for the organization.

Let’s consider user Lee from Skill Crafterz for whom we enabled unlimited archiving. Below is the sequence of events that occur when the Archive and Auto-Expanding Archive is enabled for a user.

• Once the archive mailbox is enabled, additional storage of 100 GB is added with a warning at 90 GB is provisioned as archive storage for Lee.
  • Once Lee’s archive mailbox reaches the 100 GB limit, the archive process will stop.
  • To request additional storage, Skill Crafterz Exchange administrator would have to reach out to Microsoft in the past, but now they can enable Auto-Expanding Archive for Lee.
• Once the auto-expanding archive is enabled, Lee’s archive mailbox is converted to an auto-expanding archive.
  • Microsoft automatically adds more storage to Lee’s archive mailbox when it nears the current storage limit, and this keeps on incrementing until it reaches the size of 1.5 TB.

• You need to be an Exchange Administrator to configure archives for mailboxes in Office 365.
• You should have the archive mailbox enabled to enable the auto-expanding archive feature.
• The mailbox needs to be assigned an Exchange Online Plan 2 license or an additional license of Exchange Online Archiving to enable this feature. Some higher bundled plans already include this feature like Office 365 E5 & Microsoft 365 E5.
• For enabling this feature on shared mailboxes, you need to license them with the above licenses as well.
• You need Exchange Online PowerShell to enable Auto-expanding archive. This feature cannot be enabled from the GUI.

• Archive can be enabled from UI from the Compliance Admin Center
  • Browse to the Information Governance page

• • Select the user you want to enable archive for and select enable archive

• Archive can be enabled from UI from the Classic Exchange Admin center
  • Browse to Recipients and select Mailboxes

• Select the user and click on Enable under in-place archiving

• Archive can be enabled for a specific mailbox using the below PowerShell command

• Archive can be enabled for a specific mailbox using the below PowerShell command

Auto-Expanding Archive can be enabled only via Exchange Online PowerShell. The Exchange admin center or the Security & Compliance Center cannot be used to enable the Auto-expanding archive.

• Command to enable Auto-expanding archive per mailbox

• Command to enable Auto-expanding archive for organization

Tip: You can reach out to us if you have any complex requirements where you need different policies for different sets of users in a dynamic way.

Auto-expanded archive messages can only be accessed from the following outlook clients.

• Outlook 2016 or Outlook 2019 for Windows
• Outlook Web Access (OWA)
• Outlook 2016 or Outlook 2019 for Mac

Searching items from the auto-expanded archive is available only via the following clients.

• Outlook Desktop in Current Channel (Preview)
• Outlook web access (OWA)

• Auto-expanding archive feature is not available in any of the Exchange on-prem versions.
• In hybrid exchange deployment auto-expanding archiving cannot be enabled for a specific mailbox whose primary mailbox is on-premises using the command Enable-Mailbox -AutoExpandingArchive. You need to enable Auto-Expanding Archive for the entire organization using the below command.

• Auto-Expanding archive is only supported for mailboxes with a growth rate of less than 1GB.

This article helps you set up an auto-expanding archive or unlimited archive on Office 365 mailboxes. More importantly, we have discussed the key features of archiving that helps you decide how and why you need to enable auto-expanding archives for your users.