Microsoft has announced a significant increase in mailbox storage for its Microsoft 365 Business Basic, Standard, and Premium users. As part of its 2026 updates, the company has doubled the mailbox capacity from 50 GB to 100 GB, enhancing the storage capabilities for eligible users.
Details of the Storage Expansion
The rollout of this storage upgrade began in June and is projected to continue until September. Microsoft has communicated these changes to users in advance through tenant notifications in the Message Center. However, this upgrade is limited to the primary mailbox and does not automatically extend to archive mailboxes or other Exchange Online Plan 2 benefits.
The increased capacity is facilitated through two Exchange-related service plans. The existing BPOS_S_STANDARD plan continues to provide the initial 50 GB, while the new EXCHANGE_STORAGE_50GB plan adds an additional 50 GB. Both plans need to be enabled for users to benefit from the full 100 GB capacity.
Implementation and Verification
Administrators are advised to verify service plan allocations in the Microsoft 365 admin center. This can be done by navigating through Users > Active users > Licenses and apps. Additionally, Microsoft Graph PowerShell can be employed to check service plan details, ensuring that users receive the intended storage increase.
It’s important to note that Exchange Online Plan 1 licenses remain unaffected by this change, maintaining a 50 GB limit. Furthermore, organizations should be aware that assigning multiple Exchange licenses to a single user does not stack storage quotas beyond the highest entitlement available.
Impact on Existing Quotas and Administration
Microsoft has clarified that this automatic increase will not alter any pre-set mailbox quotas established by administrators. For example, if a mailbox quota was previously reduced to 20 GB, it will remain unchanged despite the new service plan addition. This approach safeguards organization-specific mailbox management policies.
Administrators can check current mailbox quotas through Exchange Online PowerShell, ensuring that any eligible user without a custom quota receives the updated 100 GB limit. It is crucial to understand that users within the same tenant may experience staggered updates due to the licensing process.
Microsoft advises against removing and reassigning Exchange licenses to expedite the update, as this can disrupt service access and impact data retention processes. Instead, adherence to standard licensing procedures is recommended to ensure seamless implementation of the new storage capabilities.
This update represents a strategic enhancement in Microsoft’s offerings, providing increased value to its business-oriented services and supporting organizational needs for greater mailbox storage.
