On July 10, 2026, Microsoft began upgrading eligible Business Premium mailboxes to 100 GB, erasing a long-standing differentiator between the small-business plan and enterprise E3/E5 licenses. The move, confirmed in a community announcement and reported on WindowsForum, means thousands of organizations that tacked on Exchange Online Plan 2 solely for the larger mailbox can now reconsider. But tearing down those extra licenses without a proper review could strip away archive access, break compliance holds, or leave shared mailboxes stranded at the old limit.
The 50 GB Ceiling Is Lifting—But Not Everywhere at Once
For years, the official Exchange Online limits page has drawn a hard line: Business Basic and Standard users got 50 GB primary mailboxes; Business Premium matched that, while Enterprise E3/E5 enjoyed 100 GB. The new service change, first spotted in the wild by WindowsForum members and later confirmed by Microsoft, selectively bumps Business Basic, Standard, and Premium primary mailboxes to the 100 GB tier.
The rollout is not instantaneous or universal. Microsoft’s published limits documentation, as of this writing, still lists Business Premium at 50 GB—a classic Redmond disconnect between live services and static help pages. That means you cannot assume a user has the new quota just because their plan qualifies. You have to check the mailbox itself.
Open the Exchange admin center, navigate to Recipients > Mailboxes, select the user, and inspect usage details. The interface shows both current consumption and the hard ceiling. For a scripted audit, drop into Exchange Online PowerShell:
Install-Module ExchangeOnlineManagement -Scope CurrentUser
Connect-ExchangeOnline
Get-Mailbox [email protected] |
Format-List DisplayName,PrimarySmtpAddress,IssueWarningQuota,ProhibitSendQuota,ProhibitSendReceiveQuota
The ProhibitSendReceiveQuota value tells you the real limit. If it reads 100 GB, the user got the bump; if it’s still 50 GB, they haven’t. Microsoft hasn’t published a completion timeline, so you may see a mix across your tenant for weeks or months.
More Than a Bigger Inbox: What Plan 2 Actually Unlocks
It’s tempting to treat the 100 GB mailbox as a like-for-like replacement and immediately deassign Exchange Online Plan 2. The calculus, however, involves three separate storage and protection dimensions: primary mailbox capacity, online archive, and compliance-driven holds.
Primary mailbox—The headline change. If the applied quota is 100 GB, this specific need is met without Plan 2.
Online archive—Here, the Microsoft Learn page complicates the story. It shows Business Premium already includes an archive mailbox with 1.5 TB capacity when auto-expanding archiving is enabled (the same as Plan 2). So for pure archive storage, Business Premium appears sufficient. Yet WindowsForum administrators caution that some advanced archiving settings—particularly auto-expanding archive provisioning itself—may rely on the Plan 2 license assignment depending on how the tenant was originally configured. Before removing a license, verify that the archive is functioning and, if auto-expanding was explicitly set up, test whether it persists after the license change.
Check archive state with:
Get-Mailbox [email protected] |
Format-List DisplayName,ArchiveStatus,ArchiveQuota,ArchiveWarningQuota,AutoExpandingArchiveEnabled
If ArchiveStatus is Active and contains business-critical data, document its size and configuration before proceeding.
Compliance and holds—This is where Plan 2 often proves sticky. Microsoft Purview features—retention policies, retention labels, eDiscovery holds, and litigation holds—do not necessarily come bundled with Business Premium. While the plan includes some basic retention, more sophisticated compliance capabilities commonly require Exchange Online Plan 2, E3/E5, or standalone add-ons. If a user’s mailbox is subject to a hold configured in the Purview compliance portal, removing Plan 2 could violate a legal or regulatory obligation.
Using PowerShell to connect to the Security & Compliance endpoint, inventory active policies:
Connect-IPPSSession
Get-RetentionCompliancePolicy | Format-Table Name,Enabled,Mode
Get-CaseHoldPolicy | Format-Table Name,CaseId,Enabled
In the compliance portal, navigate to Data Lifecycle Management > Retention policies and eDiscovery > Cases to see what covers the mailbox. If a mailbox is held, do not remove Plan 2 until you’ve confirmed with your compliance team that the hold will remain valid under the new licensing stack.
Before You Remove That License: The Verification Checklist
A disciplined, four-step review prevents a cost-cutting move from becoming a data-loss or compliance disaster.
- Confirm the 100 GB quota is live. Use the Exchange admin center or the
Get-Mailboxcmdlet. Don’t infer it from the tenant-wide announcement. - Check mailbox usage. Run
Get-EXOMailboxStatistics -Identity [email protected] | Format-List TotalItemSize,ItemCount. If the mailbox is already near 50 GB, the increase is critical; if it’s empty, you may not need Plan 2 anyway. - Audit the archive. Is
ArchiveStatusactive? Does the archive contain messages (checkGet-EXOMailboxStatistics -Archive)? If yes, verify whether Business Premium alone maintains that archive after the add-on is removed. In many tenants, it will—but test with a pilot group first. - Review all holds and retention labels. Even a single eDiscovery case on a mailbox is a reason to pause. Consult your organization’s records manager or legal team.
Document the before-state (quotas, archive status, hold info) in a change record. Then remove the standalone Exchange Online Plan 2 assignment through the Microsoft 365 admin center or PowerShell, and re-run the same checks afterward. Compare snapshots to catch any unintended downgrade.
Shared Mailboxes Are a Different Animal
The Business mailbox increase applies to user mailboxes only. Shared mailboxes—the catch-all accounts for sales, support, and team collaboration—are not part of this uplift. Microsoft’s stated limit for an unlicensed shared mailbox remains 50 GB. To push a shared mailbox to 100 GB, you must assign an Exchange Online Plan 2 license (or an Enterprise E3/E5 license).
Run this quick inventory before any license cleanup:
Get-Mailbox -ResultSize Unlimited -RecipientTypeDetails SharedMailbox |
Select-Object DisplayName,PrimarySmtpAddress,ProhibitSendReceiveQuota,ArchiveStatus |
Export-Csv .\SharedMailboxAudit.csv -NoTypeInformation
If a shared mailbox is approaching 50 GB and your organization relies on it, keep or add a Plan 2 license. Treat shared mailboxes as a completely separate licensing case—don’t simply apply the same logic you use for individual users.
How We Got Here
Microsoft has layered Exchange Online storage tiers since the service launched, but the gap between Business and Enterprise plans widened as mailboxes grew heavier. Business Premium, despite its “premium” label, shipped with the same 50 GB ceiling as basic plans. The workaround for many small and midsize businesses was a $4-per-user Exchange Online Plan 2 add-on, doubling the primary mailbox limit and unlocking archive capabilities.
Pressure to close that gap mounted as Microsoft pushed customers toward Microsoft 365 Business Premium for its security and device management features. A 100 GB mailbox was table stakes in the enterprise world, and competitors offered it without add-ons. The rollout that began in mid-2026 is the belated answer, though Microsoft has made little public fanfare about it.
What to Expect Next
Microsoft’s official documentation will almost certainly catch up—edits to the Exchange Online limits page are likely to show Business Premium user mailboxes at 100 GB, though the timing is anyone’s guess. The rollout will continue in waves, and tenants with a mix of old and new quotas will gradually normalize.
In the meantime, make a calendar appointment to re-audit your tenant’s mailbox licensing after each major service update. A short PowerShell script run monthly can flag mailboxes that have quietly received the quota increase, letting you reclaim Plan 2 licenses only when it’s safe. The immediate savings are real: for a 200-person company, dropping Plan 2 where it’s no longer needed could trim nearly $10,000 a year. But a single litigation hold mistakenly broken costs far more.