Exchange mailboxes increased to 100GB
- Maxime Hiez
- Exchange
- 27 Aug, 2026
Introduction
On August 19, 2026, the Exchange team detailed a licensing change that went relatively unnoticed ; the Microsoft 365 Business Basic, Business Standard and Business Premium suites now include 50GB of additional storage for the primary mailbox, raising the maximum supported quota from 50GB to 100GB.
The change has been rolling out since June 2026 and should be completed in September 2026, with advance notice through the Message Center of the Microsoft 365 Admin Center for each tenant.
How the quota is built
The increase doesn’t come from a modification of the default quota, but from the addition of two service plans :
- BPOS_S_STANDARD : Grants the base 50GB
- EXCHANGE_STORAGE_50GB : Adds the additional 50GB
Both plans must be enabled on the user for the quota to reach 100GB. A disabled plan, inherited from a license template or from an old manual deactivation, leaves the user at 50GB without any error message. This is the main checkpoint before announcing the change to the users.
Two limits to know
The first one concerns archiving. The increase only covers the size of the primary mailbox and doesn’t open any online archive capability. An organization that was looking to solve a retention problem this way will still have to go through a license that includes archiving.
The second one concerns custom quotas. If an administrator has defined a specific quota value on a mailbox, that value remains in effect and isn’t replaced by the automatic addition of the 50GB. A fleet where quotas have been capped on purpose, to contain the volume or to force the use of archiving, will therefore see no change as long as those values aren’t reviewed.
Check the actual state of the mailboxes
The control is done from Exchange Online PowerShell :
Connect-ExchangeOnline
Get-Mailbox -ResultSize Unlimited | Select-Object DisplayName, ProhibitSendReceiveQuota, UseDatabaseQuotaDefaultsA UseDatabaseQuotaDefaults value set to False flags a mailbox whose quota has been set manually, and therefore excluded from the automatic increase. On the licensing side, checking that both service plans are enabled is done from the Microsoft 365 Admin Center or with Microsoft Graph PowerShell.
note
Conclusion
A quota increase at no extra cost is good news, but it doesn’t apply automatically to everyone. Two checks are needed : both service plans enabled on the users concerned, and the existence of custom quotas that neutralize the addition. For the organizations that used the 50GB ceiling as a document governance lever, this is also the opportunity to review the retention policy rather than letting the mailboxes double in volume.
Sources
Microsoft Learn - Exchange Online limits
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