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Microsoft 365

Exchange Online mailbox sizes are doubling

Stephen Brown is a product marketing manager on the Exchange team

The size of user mailboxes in all Exchange Online and Office 365 service plans is doubling. Beginning today, the current 25 GB of mailbox storage is increasing to 50 GB. With this increase even the most active email users don’t have to worry about mailbox size limitations-we’ve got you covered! There’s no price increase associated with this change. Our doubling of your mailbox storage is simply part of our promise to continuously deliver value to our Office 365 customers. 

You don’t need to do anything to take advantage of this new mailbox size. Your mailbox size will automatically be increased. The increase starts rolling out to customers today and continues through November.

December 2 2013 Update: Most customers have received the mailbox increase by the end of November.  The few remaining customers can expect the increase by the end of Q1 2014.  You can manually force the increase using remote powershell.  See the guidance at the end of this post.

This increase to a 50 GB mailbox per user benefits Exchange Online and Office 365 service plans, including: Exchange Online Plan 1, Office 365 Small Business, Midsize Business, Enterprise E1, Government G1, and Education A1. If you have one of our premium service plans (Exchange Online Plan 2, Office 365 Enterprise E3 and E4, Government G3 and G4, Education A3 and A4), you already enjoy unlimited email storage through your personal archive, but now your default primary mailbox size is increasing to 50 GB. Kiosk user mailboxes are doubling in size, too-from 1 GB to 2 GB. 

In addition to doubling the storage in your users’ primary mailbox, we’ve increased the size of other mailboxes to help you work even more productively. Shared mailboxes and Resources mailboxes are both increasing to 10 GB (more than doubling), so you’ll have plenty of room to store everything you need for your projects and collaborations. The size of Site mailboxes remains unchanged. 

Here’s a summary of the new mailbox sizes by plan:


For complete details about mailbox types and sizes, read the Office 365 service descriptions


Guidance to manually increase your mailbox size using powershell.

Refer to the guidance in the article How to set Exchange Online mailbox sizes and limits in the Office 365 environment.  The new limits for your associated plan can be found in the Office 365 service description.  As noted in the service description, the new values and commands are:

For increasing from 25GB to 50GB:

Set-Mailbox -ProhibitSendQuota 49.5GB -ProhibitSendReceiveQuota 50GB -IssueWarningQuota 49GB

For mailboxes increasing from 1GB to 2GB:

Set-Mailbox -ProhibitSendQuota 1.98GB -ProhibitSendReceiveQuota 2GB -IssueWarningQuota 1.96GB


–Stephen Brown

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