Increase Mailbox Size in Office 365: A Comprehensive Guide

Office 365 offers numerous advantages, including secure, global access to your data. You can effortlessly update documents or spreadsheets with versioning, and previous file versions are readily available. However, just like any service, Office 365 has its limitations. You can only utilize the features available within your Microsoft 365 subscription. It’s crucial to stay informed about these limitations and manage your mailbox effectively. You can check your current mailbox size and usage through the mailbox usage section of the Office 365 Admin Center or the Exchange Online Admin Center.

Mailbox Size Notifications

Depending on your mailbox size, you’ll receive different notifications:

• Warning Notification: Users receive a warning email when their mailbox exceeds a specified limit. This notification prompts users to delete non-essential emails.
• Prohibit Send Notification: If the mailbox reaches its maximum size, a prohibit-send notification is sent, preventing any further outgoing messages until space is made available.
• Block Send/Receive: If the mailbox exceeds its limit, Office 365 will block incoming emails, sending a Non-Delivery Report (NDR) to the sender. To resume receiving emails, users must delete excess messages from their inbox.

Mailbox Size Limits by Plan

Here’s a breakdown of the mailbox size limits for each Office 365 plan:

Office 365 Plan	User Mailboxes	Archive Mailboxes	Shared Mailboxes	Resource Mailboxes	Site Mailboxes	Public Folder Mailboxes	Group Mailboxes
Business Essentials	50 GB	50 GB	50 GB	50 GB	50 GB	50 GB	50 GB
Business Premium	50 GB	50 GB	50 GB	50 GB	50 GB	50 GB	50 GB
Enterprise E1	50 GB	50 GB	50 GB	50 GB	50 GB	50 GB	50 GB
Enterprise E3	100 GB	Unlimited	50 GB	50 GB	50 GB	100 GB	50 GB
Enterprise E5	100 GB	Unlimited	50 GB	50 GB	50 GB	100 GB	50 GB
Enterprise F3	2 GB	Not Available	50 GB	50 GB	Not Available	Not Available	50 GB

Key Facts About Office 365 Mailbox Storage

• Users can access 100 GB of storage in their archive mailbox. Once this limit is reached, the auto-expanding option is activated.
• Shared mailboxes require an Exchange Online subscription. Without a license, they can hold only 50 GB, but this can be increased to 100 GB with the appropriate subscription.
• Resource mailboxes do not require a license, with a default size of 50 GB. Users can increase this size by obtaining an Office 365 E3 or E5 subscription.

Increase Office 365 Mailbox Size with PowerShell

For those familiar with Windows PowerShell commands, increasing mailbox size is a straightforward process. Follow these steps to expand the mailbox size for your Office 365 accounts:

1. Open Windows PowerShell: Start PowerShell as an administrator. Right-click the Windows PowerShell icon and select Run as administrator.
2. Create a New Session: Run the following command to create a new Exchange Online session:

   $UserCredential = Get-Credential
   $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection

3. Import Cmdlets: Import the Exchange Online cmdlets into your local session with:

   Import-PSSession $Session -DisableNameChecking

4. Check Mailbox Size: Use this command to view the current mailbox size limit:

   Get-Mailbox <UserID> | Select-Object *quota

5. Increase Mailbox Size Limit: To expand your mailbox size limit to 100 GB, run:

   Set-Mailbox <UserID> -ProhibitSendQuota 99GB -ProhibitSendReceiveQuota 98GB -IssueWarningQuota 98GB

Example:

   Set-Mailbox charlie@yourmail.com -ProhibitSendQuota 99GB -ProhibitSendReceiveQuota 98GB -IssueWarningQuota 98GB

6. Apply Changes to Multiple Users: To increase the mailbox size for a group, you can use:

   Get-User | Where-Object { $_.Team -eq "Developer" } | Get-Mailbox | Set-Mailbox -ProhibitSendQuota 99GB -ProhibitSendReceiveQuota 98GB -IssueWarningQuota 98GB

Note: Administrator privileges are required to make changes to multiple accounts.

7. Limit Mailbox Size for All Users: To set a mailbox size limit for all users in your organization, use:

   Get-Mailbox | Set-Mailbox -ProhibitSendQuota <Value> -ProhibitSendReceiveQuota <Value> -IssueWarningQuota <Value>

8. End the Session: Once all changes are made, terminate the session with:

   Remove-PSSession $Session

Conclusion

If you are comfortable using Windows PowerShell, following the above steps allows you to increase the mailbox size for individual or multiple Office 365 accounts. Keep in mind that this will not alter other limitations, such as mailbox folder limits, retention limits, and moderation limits. It’s recommended to use SoftMagnat Office 365 Backup tool before increasing mailbox sizes. Check for any additional restrictions that might need adjustment to fully utilize your increased mailbox storage.

FAQs

How can I check my current mailbox size?

• You can check your mailbox size by visiting the mailbox usage section in the Office 365 Admin Center or Exchange Online Admin Center.

What happens if I exceed my mailbox size limit?

• Exceeding your mailbox limit results in a warning email, followed by restrictions on sending and receiving messages until you free up space.

Can I increase my mailbox size without PowerShell?

• Increasing mailbox size typically requires PowerShell commands, but you can also upgrade your Office 365 plan for larger mailbox limits.

Will my email performance be affected if I reach the limit?

• Yes, reaching your mailbox size limit can hinder email performance, including the inability to send or receive new messages.

Can I store emails locally if my mailbox is full?

• Yes, you can save emails locally on your system to free up space in your Office 365 mailbox.