MC1191923 - Microsoft Purview | Data lifecycle management – Auto archive for Exchange Online

Introduction

We’re introducing Auto Archiving for Exchange Online to help prevent mail flow disruptions caused by mailboxes reaching their storage quota. This update ensures real-time mailbox health monitoring by automatically moving the oldest items to the archive when mailbox usage exceeds 96% of its quota. This feature addresses customer feedback for proactive mailbox space management and helps maintain business continuity.

When this will happen:

• Public Preview: Rollout began in mid-November 2025 and is expected to complete early December 2025
• Worldwide rollout: Rollout begins in early January 2026 and is expected to complete late January 2026

How this affects your organization:

Who is affected: Admins managing Exchange Online mailboxes with provisioned archive mailboxes.

What will happen:

• When a primary mailbox exceeds 96% of its quota, Managed Folder Assistant will automatically archive the oldest items until usage drops below the threshold.
• Applies to both IPM folders and Recoverable Items folders.
• Honors Never Move to Archive tags.
• Enabled by default for all tenants.
• Archive mailbox must be provisioned and have available space for auto-archiving to occur.

What you can do to prepare:

• No immediate action is required unless you want to adjust or disable this feature.
• To disable auto-archiving for a mailbox:

  Set-Mailbox <user-smtp-address> -AutoArchivingEnabled $false

• To adjust the organization-level threshold (default = 96%, valid range = 80–100):

  Set-OrganizationConfig –AutoArchivingThresholdPercentage <value>

• If set to 100, auto-archiving will not occur for the tenant.
• Review internal documentation and communicate this change to helpdesk staff.

Learn more:

• Auto-archiving in Exchange Online | Microsoft Learn

Compliance considerations:

No compliance considerations identified, review as appropriate for your organization.