Enable Auto-Expanding Archive in Microsoft 365 Print

Overview

Auto-expanding archiving in Microsoft 365 allows archive mailboxes to grow automatically up to 1.5 TB as storage is needed. Once the archive mailbox reaches 90 GB, Microsoft 365 begins provisioning additional storage automatically — no manual intervention required.

This feature is configured via Exchange Online PowerShell only. It cannot be enabled from the Exchange Admin Center or the Microsoft Purview portal.

Prerequisites

• You must be a Global Administrator or a member of the Organization Management role group in Exchange Online. To enable for specific users only, membership in a role group with the Mail Recipients role is sufficient.
• The user's mailbox must already have an archive mailbox enabled before auto-expanding archiving can be turned on.
• Auto-expanding archiving requires one of the following licenses:
  • Exchange Online Plan 2 (included in Microsoft 365 E3, E5, and Business Premium)
  • Exchange Online Plan 1 + Exchange Online Archiving add-on
• The Exchange Online PowerShell module must be installed. If not yet installed, run the following in PowerShell as Administrator:

Install-Module -Name ExchangeOnlineManagement -Force -AllowClobber

Step 1 – Connect to Exchange Online PowerShell

Open PowerShell as Administrator and connect to your tenant. Replace the UPN with your admin account:

Connect-ExchangeOnline -UserPrincipalName admin@yourdomain.com

A modern authentication window will appear. Sign in with your administrator credentials.

Step 2 – Enable Auto-Expanding Archiving

Choose one of the two methods below depending on your needs:

Option A – Enable for the entire organization (all users):

Set-OrganizationConfig -AutoExpandingArchive

This enables auto-expanding archiving for all existing and future mailboxes in your organization. New mailboxes will still require an archive mailbox to be individually enabled first.

Option B – Enable for a specific user only:

Enable-Mailbox user@yourdomain.com -AutoExpandingArchive

Replace user@yourdomain.com with the user's email address. The user's archive mailbox must already be active before running this command.

Step 3 – Verify Auto-Expanding Archiving is Enabled

To verify at the organization level:

Get-OrganizationConfig | FL AutoExpandingArchiveEnabled

A result of True confirms it is enabled organization-wide.

To verify for a specific user:

Get-Mailbox user@yourdomain.com | FL AutoExpandingArchiveEnabled

A result of True confirms it is enabled for that user.

To check inactive mailboxes:

Get-Mailbox -InactiveMailboxOnly | FL UserPrincipalName,AutoExpandingArchiveEnabled

Notes

• It can take up to 30 days after enablement for the additional archive storage to be provisioned.
• When enabled per-user (Option B) and the mailbox is on hold or assigned a retention policy, the archive mailbox quota is increased by an extra 10 GB immediately as a buffer while provisioning takes place.
• Running Set-OrganizationConfig -AutoExpandingArchive does not change the AutoExpandingArchiveEnabled flag on individual mailboxes to True — this is expected behavior and does not indicate a problem.
• Auto-expanding archiving is supported for shared mailboxes as well as user mailboxes.
• Auto-expanding archiving is not supported for on-premises mailboxes in any version of Exchange Server.