Exchange Online

How to Export the Shared Mailbox Size Report in Microsoft 365

Shared mailboxes in Microsoft 365 are designed to facilitate collaborative email management from a centralized email address. While these mailboxes experience heavy traffic, the storage consumption can disrupt communication and lead to missed messages. Therefore, monitoring the size of Exchange Online shared mailboxes is essential. You can use the following methods to seamlessly obtain a Microsoft 365 shared mailbox size report.

Check Shared Mailbox Size Using Microsoft 365 Admin Center

Microsoft 365 Permission Required

Reports Reader Least Privilege

Global Admin Most Privilege

Login to the Microsoft 365 admin center.
Navigate to Reports»Usage»Exchange»Mailbox usage.
Add the Recipient Type column and sort it in ascending order to display all the shared mailbox storage limits with their current usage at the top.
You can also add other columns like prohibit send/receive quota, issue warning quota, etc., to get all shared mailbox storage details.
Use the Export option to save the shared mailbox size report on your local machine.

Check Shared Mailbox Size Using Microsoft 365 Admin Center

Get Shared Mailbox Size Using PowerShell

Microsoft 365 Permission Required

View-Only Recipients role Least Privilege

Global Admin Most Privilege

Connect to the Exchange Online PowerShell module.
Windows PowerShell
```
 Connect-ExchangeOnline
```
Execute the following command to list all shared mailboxes with their storage metrics, such as total item size, issue warning quota, prohibit send/receive quota, etc.

 Windows PowerShell 
 Get-Mailbox -ResultSize Unlimited -RecipientTypeDetails SharedMailbox | ForEach-Object {
    $mailboxStats = Get-MailboxStatistics -Identity $_.UserPrincipalName
    [PSCustomObject]@{
        DisplayName = $_.DisplayName
        TotalItemSize = $mailboxStats.TotalItemSize
        IssueWarningQuota = $_.IssueWarningQuota
        ProhibitSendQuota = $_.ProhibitSendQuota
        ProhibitSendReceiveQuota = $_.ProhibitSendReceiveQuota
    }
} | Format-Table

Get Shared Mailbox Size Using PowerShell

Export Shared Mailbox Size Report Using PowerShell Script

Microsoft 365 Permission Required

View-Only Recipients role Least Privilege

Global Admin Most Privilege

PowerShell scripting helps to export detailed storage data for all shared mailboxes for further analysis.
So, we’ve crafted a script that exports Exchange Online shared mailbox storage usage report in a more efficient and user-friendly manner.
Download and run the following script in the Windows PowerShell.

Export Shared Mailbox Size Report Using PowerShell Script

GetSharedMailboxSizeReport.ps1

Simple & Quick
Get Shared Mailbox Size Report Using AdminDroid

AdminDroid Permission Required Delegated

Any user with report access delegated by the Super Admin.

Login to the AdminDroid Office 365 reporter.
Navigate to the Mailbox Size Over Time report under Reports»Exchange»Shared Mailbox Info»Mailbox Size Over Time.
This report helps check shared mailbox size growth in Exchange Online. It helps identify mailboxes that are nearing their full storage capacity with details like mailbox size, used percentage, item count, and size growth by daily usage.

Get Shared Mailbox Size Report Using AdminDroid

AdminDroid Exchange Online Reporter

Efficiently Level Up Your Shared Mailbox Storage Management!

The AdminDroid Exchange Online reporting tool provides comprehensive data to check shared mailbox size and its usage with a thorough understanding. Serving as a one-stop shop, AdminDroid allows you to monitor shared mailbox storage, size growth statistics, email traffic, and more for optimal resource allocation!

Visualize Shared Mailbox Insights

Check shared mailbox storage details and gain clear insights through the Exchange Online dashboard for a complete bird’s-eye view.

Regular Updates on Shared Mailbox Storage

Obtain real-time insights with the scheduling feature to get Exchange shared mailboxes info along with the storage insights and take necessary actions before quota limits are reached.

Instant Alerts on Mailbox Peak Hours

Proactively monitor shared mailbox peak hours and days at which the maximum number of emails are sent and received using custom Microsoft 365 alert policies.

Review Shared Mailbox Quota in Exchange Online

Leverage the Recipient Type Details filter in the mailbox quota report to easily view all shared mailboxes along with their mailbox quota, archive quota, and recoverable items quota.

Detailed Information on Mailbox Storage

Easily check mailbox size in Office 365 for all users and monitor current storage trends to address any Exchange Online mailbox size issues.

Find and Remove Litigation Hold from Shared Mailboxes

Identify the shared mailboxes with litigation holds that are capable of retaining deleted items and remove unnecessary holds to optimize storage.

In summary, AdminDroid's Exchange Online management empowers you to effectively track, export, and manage shared mailbox storage, particularly by identifying mailboxes nearing capacity. Ultimately, this ensures optimal mail flow in shared mailboxes, minimizing disruptions and message loss.

Explore a full range of reporting options

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Important Tips

Block shared mailbox sign-ins and protect your sensitive contents to avoid the risk of unauthorized access through auto-generated passwords.

Report suspicious messages in shared mailboxes using the built-in report button to easily identify and prevent Microsoft 365 phishing & junk emails.

Utilize message trace in Exchange Online for shared mailboxes to trace the status of target messages, such as received, rejected, delivered, or deferred.

Common Errors and Resolution Steps

Below are potential errors you may encounter and troubleshooting hints when dealing with shared mailbox storage issues.

Error The sender's submission quota was exceeded.

This error occurs when you try to send more than 10,000 messages in the last 24 hours.

Fix Wait for one day to send emails from the shared mailbox.

Error Your mailbox is almost full.

This error occurs when your shared mailbox quota warning is reached.

Fix To resolve this error, increase the shared mailbox storage by assigning a license, or mail deletions. To temporarily bypass this error, change the issue warning quota using the following cmdlet.

Set-Mailbox "<SharedMailboxUPN>" -IssueWarningQuota "<SizeInKB>"

Error Your mail server's send quota has been exceeded. Please contact your mail admin or try re-sending from a different email account. Your email has been returned to your drafts folder.

This error occurs when your shared mailbox storage reaches the prohibited send quota.

Fix To resolve this error, optimize the shared mailbox storage by assigning a license, or mail deletions. To temporarily bypass this error, increase the prohibit send quota using the following cmdlet.

Set-Mailbox "<SharedMailboxUPN>" -ProhibitSendQuota "<SizeInKB>"

Error You've exceeded the storage limit for your mailbox. Delete some items from your mailbox.

This error signifies that the shared mailbox usage is full, and it has exceeded its assigned storage limit.

Fix To address this issue, archive older items and clear the deleted items folder to remove unnecessary messages. Additionally, consider utilizing an auto-expanding archive for expandable storage and implementing a litigation hold to retain deleted mails.

Error Get-MgSubscribedSku : Insufficient privileges to complete the operation

This error typically occurs when the user executing the cmdlet does not have the necessary permissions or appropriate scopes to perform the operation.

Fix Connect to the Microsoft Graph PowerShell using the Directory.ReadWrite.All scope to ensure sufficient permissions for the operation.

Connect-MgGraph -Scope Directory.ReadWrite.All

Error BootResult: accessDenied Back Filled Errors: Unhandled Rejection: Error: 500: undefined|undefined: undefined err: Microsoft.Exchange.Data.StoreObjects.AccessDeniedException

This error occurs when the user's access rights are not correctly configured or have been removed for the shared mailbox. It also occurs when permissions have been recently granted.

Fix To resolve this, check the access rights of the user for the shared mailbox. If they are correctly configured, wait for some time and try opening the shared mailbox again.

Exchange Online

Frequently Asked Questions

Manage Shared Mailboxes Storage Usage in Microsoft 365

What to do if a shared mailbox is full in Microsoft 365?

What is the default limit of shared mailboxes in Exchange Online?

How to increase the shared mailbox size in Microsoft 365?

How to check shared mailbox usage in Microsoft 365?

Can a user access the shared mailbox storage details?

How to manage a large shared mailbox in Microsoft 365?

1. What to do if a shared mailbox is full in Microsoft 365?

If your shared mailbox is reaching its storage limit, take the following actions to maintain a smooth mail flow and prevent bounce-backs of incoming emails with non-delivery reports.

Find and delete outdated emails that are no longer required.
Consider implementing a retention policy to automatically delete emails after a specified period.
Clear unnecessary emails in the shared mailbox with large attachments.
Assign a license to a shared mailbox to increase its storage quota.
Enable archive for the shared mailbox to provide separate additional storage and automate email retention.

2. What is the default limit of shared mailboxes in Exchange Online?

Refer to the following points to know the default storage limit of a shared mailbox in Microsoft 365.

Issue warning quota: If the shared mailbox is nearing its storage limit, members will receive a warning that the mailbox is approaching its storage quota. By default, the threshold is set to 49 GB.
Prohibit send quota: Once a shared mailbox reached its maximum storage limit (49.5 GB by default), delegated users are unable to send new emails. However, they can still receive new emails and access existing ones.
Prohibit send or receive quota: If a shared mailbox limit is consumed fully (i.e., 50 GB), delegated users are unable to send, receive, or access emails in the mailbox.

However, these limits can be increased by assigning a more advanced license. Additionally, shared mailbox storage quotas can be adjusted within the total storage limit provided by the assigned license based on the organization's specific requirements.

3. How to increase the shared mailbox size in Microsoft 365?

By default, shared mailboxes in Exchange Online come with a storage of 50 GB. To increase a shared mailbox to 100 GB, you will need at least the Exchange Online Plan 2 license.

Assign license to a shared mailbox using Microsoft 365 admin center

Assigning a license to a shared mailbox is similar to assigning a license to a user. You can do the following steps in the Microsoft 365 admin center.

Go to the Active users tab under the Users section and choose the appropriate shared mailbox from the list.
Navigate to the License and apps page and select the appropriate license. After that, click on Save changes.

Assign license to a shared mailbox in Microsoft 365 Using PowerShell

To increase the shared mailbox size in Microsoft 365 using powershell by assigning a license, follow the steps below.

First, connect to the Microsoft Graph PowerShell and find the SKU ID of the licenses available in your Microsoft 365.
```
Connect-MgGraph -Scopes Directory.ReadWrite.All, User.ReadWrite.All
```
After that, execute the following cmdlet with the appropriate SKU ID and the UPN of the shared mailbox.
```
Set-MgUserLicense -UserId "<SharedMailboxUPN>" -AddLicenses @{SkuId= "<SKUID>"} -RemoveLicenses @()
```

You can find the appropriate SKU ID by retrieving the M365 license usage report using PowerShell.

4. How to check shared mailbox usage in Microsoft 365?

To obtain the storage usage of a specific shared mailbox, follow these steps using the Exchange admin center.

Login to the Exchange admin center and navigate to the Mailboxes tab under the Recipients section.
Select the shared mailbox from the list.
In the General tab, you can find the shared mailbox usage details, including total storage and the currently consumed percentage.

Schedule the shared mailbox size over time report using AdminDroid!

Utilize the Schedule this report now option to receive daily shared mailbox storage statistics directly in your email.
You can set the schedule frequency to daily, weekly, or monthly based on your needs.

Here's a handy tip: Utilize the Mailbox Display Name filter in the shared mailbox size over time report to track the storage trend of a particular shared mailbox.

5. Can a user access the shared mailbox storage details?

No, not every Microsoft 365 user can access a shared mailbox and utilize its storage. Only users with delegated permissions levels in Outlook shared mailboxes can access the storage and emails of a shared mailbox.

To access and view the shared mailbox storage details via the Outlook web, follow these straightforward steps:

First, open the shared mailbox in the Outlook web client.
Go to the View tab and choose the View settings option.
Then, navigate to the General tab and select the Storage option.

Here, you can view the storage size details of the shared mailbox along with the percentage used. You can also get insights about the storage occupied by emails in the inbox, sent items, drafts, and deleted items.

While users with delegated access can utilize the shared mailbox's storage and its features, it is important to regularly review the shared mailbox permission report to effectively manage access rights.

6. How to manage a large shared mailbox in Microsoft 365?

Microsoft 365 organizations can upgrade the shared mailbox subscription or remove data from the mailbox when it reaches the storage quota. As deleting emails is not a preferred or perfect solution, admins often choose to increase shared mailbox size in Office 365.

Assigning subscriptions like Exchange Online Plan 2, E1, E3, or E5 plans will double the shared mailbox storage capacity to 100 GB. However, even with the increased storage to 100 GB, it may not be sufficient for organizations with a more traffic.

In such a scenario, enabling the shared mailbox archive creates a separate archive mailbox with 50 GB of space. Moreover, with the auto-expanding archive feature in Microsoft 365, the shared mailbox archive size can be increased up to 1.5 TB.

Use the following cmdlet in the Exchange Online PowerShell module to enable auto-expanding archives for a shared mailbox.
```
Enable-Mailbox "<SharedMailboxUPN>" -AutoExpandingArchive
```
To enable auto-expanding archive in organization-wide, use the following command.
```
Set-OrganizationConfig -AutoExpandingArchive
```

Identifying archived mailboxes with auto-expanding archive enabled in Microsoft 365 is effortless with AdminDroid.

Examine the shared mailboxes with auto-expanding archives with the details, such as archive names, user principal names, auto-expanding archive status, etc.
Also, you can manage the shared mailbox storage by disabling archive for those that don't require high storage.