License & Subscription Issues

How to Fix Microsoft 365 Mailbox Limited to 15 GB Instead of 50 GB

Maira Mehtab Sep 20, 2026 869 views

Question details

The user's Microsoft 365 email account is restricting storage to 15 GB and reporting that the mailbox is full, even though they expect a 50 GB capacity from their subscription.

Product: Microsoft 365
Device & OS: not provided
Scenario: Checking email storage capacity or receiving a mailbox full notification.
Observed behavior: The mailbox displays a maximum limit of 15 GB and prevents receiving new emails once full, rather than allowing the expected 50 GB of storage.

Before you start

Log into your Microsoft account portal and have your active subscription details ready to verify your exact Microsoft 365 plan.

Solution 1Recommended

Verify Your Exchange Online Plan Capabilities

Check your Microsoft 365 subscription tier to ensure it actually includes Exchange Online and verify the storage limits for your specific plan.

Many users assume that all Microsoft 365 subscriptions come with a 50 GB mailbox. However, mailbox sizes vary strictly by plan. Some personal or basic plans only offer 15 GB, while Exchange Online Plan 1 provides 50 GB.

Access your account dashboard

Navigate to the Microsoft Account portal or the Microsoft 365 Admin Center and log in with your credentials.

Check active subscriptions

Click on 'Services & subscriptions' (for personal) or 'Billing' > 'Your products' (for business) to see your current active license.

Compare Exchange Online limits

Review the details of your specific plan. If your plan is 'Microsoft 365 Basic' or a standalone apps plan, you may only be entitled to the free 15 GB Outlook.com storage. Upgrade to a plan with Exchange Online Plan 1 to get 50 GB.

Plan Differences: Microsoft 365 Apps for business does not include email hosting. You must have Microsoft 365 Business Basic, Standard, or Premium for the 50 GB Exchange mailbox.

Solution 2

Identify the Actual Email Provider

Determine if your email is hosted by a third-party provider rather than Microsoft, which could explain the 15 GB limitation.

Free Microsoft Office alternative

Try WPS Office for Seamless and Free Document Management

If you are reviewing your Microsoft 365 subscription costs due to mailbox limits, consider switching to WPS Office. It provides a robust, lightweight, and cost-effective alternative to Microsoft Office for your word processing, spreadsheet, and presentation needs.

1. Download the installer: Visit the official WPS Office website and click the free download button.
2. Install the software: Run the downloaded setup file and follow the quick installation prompts.
3. Open and edit seamlessly: Launch WPS Office and instantly open your existing Microsoft Office files without losing any formatting.

100% compatible with Microsoft Word, Excel, and PowerPoint file formatsLightweight application that uses fewer system resources and disk spaceFree to use with an intuitive, familiar user interfaceIncludes a powerful built-in PDF toolkit for editing and converting documents

microsoft office alternative - wps office

Frequently Asked Questions

Why does my Outlook account only have 15 GB of storage?

Free Outlook.com accounts provide a baseline of 15 GB of email storage. If you purchased a Microsoft 365 plan that only includes desktop apps and not an Exchange Online license, your email account remains on the free 15 GB tier.

Does every Microsoft 365 subscription include an email account?

No. Several Microsoft 365 plans, such as Microsoft 365 Apps for enterprise or business, solely provide access to the desktop applications (Word, Excel, PowerPoint) and cloud storage, but do not include email hosting via Exchange.

How can I upgrade my mailbox limit to 50 GB?

To get a 50 GB mailbox, you need to purchase or upgrade to a Microsoft 365 plan that explicitly includes Exchange Online Plan 1, such as Microsoft 365 Business Basic, Business Standard, or a comparable enterprise plan.

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