All mailbox limits (& how to find yours) in and Microsoft hosting

An or Microsoft hosted mail storage quota can be anything from 2GB to 100GB.  Here’s a full list of the mailbox limits, how to check your current usage and total allowed size.

We’re talking here about Microsoft mailbox hosting services including NOT the various and confusing types of Outlook software. free account 15GB

All free free accounts, including older Hotmail accounts, get a 15GB mailbox. with Microsoft 365 – 50GB

If the address is linked to a Microsoft 365 Personal or Family plan you get 50GB of mailbox. That’s in addition to the 1 Terabyte of OneDrive space.

Microsoft 365 hosted mailbox – 50GB

Most Microsoft 365 hosted / Exchange Online mailboxes also have a 50GB quota.

That applies to:

  • Microsoft 365 Business Basic
  • Microsoft 365 Business Standard
  • Office 365 Enterprise E1

Office 365 Enterprise – 100GB

The high-end Exchange Online / Microsoft hosted plans get 100GB per mailbox

  • Office 365 Enterprise E3
  • Office 365 Enterprise E5

Office 365 minimal plans – 2GB

Some low cost Enterprise plans with only access to web based apps, get a mere 2GB of mailbox storage.

  • Office 365 Enterprise F3
  • Exchange Online Kiosk
  • Exchange Server 2013

Check your quota

The best way to check your use is via the web login at or for Enterprise plans.


Go to Settings | Storage to see the storage used and upper limit.

Source: Microsoft


For paid or ‘Premium’ accounts (linked to Microsoft 365 Family/Personal) go to Settings | Premium | Features to see a 50GB quota.

Enterprise / Microsoft hosted mailboxes

Settings | General | Storage to check if you have 2GB, 50GB or 100GB.

Detailed Drill down

If you’d like more detail about what folders are taking up storage, use Outlook for Windows.

Right-click on the mailbox heading in the left Navigation Pane (i.e. showing the email address) choose Data File Properties | General | Folder Size … and finally the Server Data tab.  You’ll have to wait while the server info is collated.

Unfortunately, the columns aren’t sortable (come on Microsoft, it’s 2021 for heavens sake!)

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Understandable confusion

Microsoft seems reluctant to disclose the storage limits.  If you’re confused or wasted time trying to find the answer, you’re forgiven.

A Microsoft web page labelled  Storage limits in does NOT clearly say what the storage limit is! Click on the heading “How to clean up your mailbox” and the vital information, promised in the heading, is revealed.

“Microsoft offers 15 GB of email storage space per free account. Microsoft 365 subscribers get 50 GB of space.”

Searching for terms like ‘ free mailbox size’ shows a totally wrong answer!

100GB is the limit for high-end Microsoft 365 Enterprise plans only. 

To be fair, that prominent wrong result is Google’s mistake not Microsoft’s.   Bing gives more accurate results in this case.

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