M365 Changelog: Upcoming Changes to Auto-Expanding Archive

MC288051 – Updated September 30, 2021: Microsoft has updated the content below for additional clarity. Thank you for your patience.

Microsoft will be removing the word ‘Unlimited’ from their service description and related public documentation for the auto-expanding archiving feature, and instituting a 1.5TB limit for archive mailboxes. This limit is not configurable.

Key points

• Timing: This change will take effect beginning November 1, 2021 and is applicable to all environments.
• Roll-out: tenant level
• Action: review and assess

How this will affect your organization:

Once this limit takes effect, your users will not be able to extend their online archives beyond 1.5TB. As currently noted in Microsoft’s documentation, auto-expanding archive is only supported for mailboxes used for individual users or shared mailboxes with a growth rate that does not exceed 1 GB per day. Using journaling, transport rules, or auto-forwarding rules to copy messages to Exchange Online Archiving for the purposes of archiving is not permitted. A user’s archive mailbox is intended for just that user. Microsoft reserves the right to deny auto-expanding archiving in instances where a user’s archive mailbox is used to store archive data for other users or in other cases of inappropriate use.

If you have previously worked with Microsoft Support to provide exceptions for existing archives exceeding 1.5TB, those specific archives will not be affected by this change. You will not, however, be able to create any new archives that exceed 1.5TB.

What you need to do to prepare:

You should check the size of archives in your organization if you are concerned that they might be close to the limit and consider deleting some of the content if you intend to continue adding to the archive. You can use Get-MailboxFolderStatistics to view archive mailbox size.