Exchange Online 2026: Microsoft doubles mailbox storage

Microsoft is doubling the storage space for Exchange Online mailboxes in certain Microsoft 365 Business plans from 50 to 100 gigabytes. The free upgrade is automatic and should be completed by September 2026.

More storage for business users

As part of the product adjustments for 2026, Microsoft is automatically expanding the storage capacity of eligible Microsoft 365 business mailboxes from 50 to 100 gigabytes. The Business Basic, Business Standard and Business Premium tariffs are affected. This means companies no longer have to purchase more expensive enterprise licenses to increase the storage limit. So far, many users have reached the limit of 50 gigabytes. If the usage exceeds 49.5 gigabytes, the system often blocks the sending of new messages. The expansion reduces the percentage utilization for the same amount of data. This gives administrators and users more flexibility for emails and large attachments.

The volume of email in companies has increased significantly over the past ten years. At the same time, the average size of documents and tables in attachments increased. While capacities of two to five gigabytes were previously sufficient for local servers, companies today often store entire communication processes in the cloud.

Technical implementation in detail

Like Microsoft in a post by TechCommunity explained, the new volume is made up of two components. The previous basic plan still provides 50 gigabytes. In addition, the user account receives a service package with an additional 50 gigabytes. The full quota is only available when both plans are active.

According to Microsoft, a combination of different licenses is not possible. If a user has a separate Enterprise plan with 100 gigabytes in addition to the business license, this maximum value remains. Manually set lower storage limits remain in place. The update does not overwrite these defaults.

Patience required during the rollout

The new capacities will be distributed gradually. The rollout is expected to be completed by the end of September 2026. As a result, within an organization, some mailboxes may already show expanded storage, while others may still remain as they were. The first administrators are also reporting isolated display errors.

Microsoft does not recommend manually removing and reassigning licenses to force expansion. This could trigger accidental deletion processes in the cloud. Price adjustments are also planned for the Business Basic and Business Standard tariffs in 2026. The price for Business Premium remains unchanged.