Download Mailboxes Usage Monitor
Elis Riebow
The Mailbox usage report provides information about users with a user mailbox and the level of activity by each based on the email send, read, create appointment, send meeting, accept meeting, decline meeting and cancel meeting activity. It also provides information about how much storage has been consumed by each user mailbox, and how many of them are approaching storage quotas. The mailbox usage report also contains information on mailboxes shared amongst users, providing storage and quota data on shared mailboxes.
To access shared mailbox information, change the drop-down selection at the top right of the charts to Shared. If your tenant does not have shared mailboxes, you will not be able to view any shared mailbox information.
The Mailbox usage report can be viewed for trends over the last 7 days, 30 days, 90 days, or 180 days. However, if you select a particular day in the report, the table will show data for up to 28 days from the current date (not the date the report was generated). The data in each report usually covers up to the last 24 to 48 hours.
The Mailbox chart shows you the total number of user or shared mailboxes in your organization, and the total number of user mailboxes that are active on any given day of the reporting period. A user mailbox is considered active if it had an email send, read, create appointment, send meeting, accept meeting, decline meeting and cancel meeting activity.
The Storage chart shows you amount of storage used in your organization by mailbox type. Storage Chart doesn't include archive mailboxes. For more information about auto-expanding archiving, see Overview of auto-expanding archiving in Microsoft 365.
If your organization's policies prevents you from viewing reports where user information is identifiable, you can change the privacy setting for all these reports. Check out the Hide user details in the reports section in the Activity Reports in the Microsoft 365 admin center.
An Exchange Online service advisory informs you about mailboxes that are on hold and at risk of reaching or exceeding their quota. These service advisories provide visibility to the number of mailboxes in your organization that might require admin intervention.
When you access the service advisory, you see a link under User Impact. Selecting that link opens a flyout window that lists affected mailbox GUIDs for your tenant. This list is limited to no more than 155 mailboxes.
If your tenant exceeds more than 155 mailboxes at or nearing their storage quota, visit your admin portal and access your mailbox usage report. Alternatively, the direct URL to the mailbox usage report is =applauncher#/reportsUsage/MailboxUsage.
The service advisories for mailbox utilization inform admins about mailboxes on hold that are nearing the mailbox storage quota. The type of holds that that can be placed on mailboxes include Litigation holds, eDiscovery hold, and Microsoft 365 retention policies (that are configured to retain data). When a mailbox is on hold, users (or automated processes) can't permanently remove data from their mailbox. Instead, admins should configure Messaging Records Management (MRM) retention policies in Exchange Online (in line with their organization's compliance policies related to data retention) to move data from a user's primary mailbox to their archive mailbox.
If a mailbox on hold doesn't have an archive and reaches a critical or warning state, admins should enable archive mailboxes and enable auto-expanding archiving. Make sure the retention period for the archive policy assigned to the mailbox (which moves email from the primary mailbox to the archive mailbox) only retains data in the main mailbox for as long as needed. If nothing is done to resolve the quota issues identified by the mailbox utilization service advisory, users might not be able to send or receive email messages or meeting invites.
If a mailbox is on hold and is nearing or has reached its quota and doesn't have an archive, an admin can enable an archive mailbox (and potentially enable auto-expanding archiving) along with ensuring an MRM archive policy is applied to the mailbox. (An MRM archive policy is a retention policy in Exchange Online that moves items to the archive mailbox.) For more information about how holds interact with quotas and recommended quota sizes for the main mailbox and Recoverable Items folder, see Increase the Recoverable Items quota for mailboxes on hold.
If a mailbox is on hold, has an archive, and is nearing or has reached its Recoverable Items Quota, an admin can increase the quota for the Recoverable Items folder. For more information, see Increase the Recoverable Items quota for mailboxes on hold.
If an admin increases the Recoverable Items Quota, they should also make sure that an MRM archive policy that moves items to the archive mailbox is applied to the mailboxes. The retention period for the archive policy must be short enough so that items aren't retained too long in the primary mailbox before they're moved to the archive.
MRM archive policies also move items from the Recoverable Items folder in the primary mailbox to the Recoverable Items folder in the corresponding archive mailbox. This capability helps prevent the mailbox from exceeding the quota for the Recoverable Items quota.
Archive retention policies can be configured in various ways, depending on your organization's needs. For detailed information about retention policies, see Retention tags and retention policies in Exchange Online. An admin can view existing retention policies by running the following command:
Administrators possess the necessary tools to evaluate the cause of a nonfunctional retention policy and address any errors. Some common scenarios of failure include the policy not being correctly applied or failure to process a mailbox.
If you don't resolve the quota issues, you can expect to see this type of service advisory every seven days. Subsequent service advisories might contain higher mailbox counts for other mailboxes that are nearing their quota. If you resolve quota issues, this service advisory only occurs when another mailbox with quota issues is identified.
a customer has asked me to get a detailed report (Mailbox Usage) for a Shared Mailbox. The 365 GUI only shows the licenced users with emails sent, received, etc but not for Shared Mailboxes. I also enabled Microsoft 365 usage analytics for PowerBI but I don;t see how to exclude/include mailboxes in there either.
Log your Office 365 global admin account to Office 365 admin center> Exchange, then In the EAC, navigate to Recipients > Shared.
In the list of user mailboxes, click the mailbox that you want to change the properties for, and then click Edit.
On the mailbox properties page, click mailbox usage to view or change properties. You can check the last Logon time and the Mailbox usage information under that section.
Example: The logic HM worker process uses to detect and create monitoring mailboxes depends on Exchange Cumulative Update (CU) installed, Exchange role installed on the box and mailbox databases present. The Following logic was used to create monitoring mailboxes for Exchange Server 2013 servers between RTM to Cumulative Update 5:
The display name of the monitoring mailbox created for database copy contained the GUID of the mailbox database for which it was created. Example: The display name of the monitoring mailbox created for CAS server contained the GUID of the Exchange server for which it was created. Example: The following logic is used to create monitoring mailbox for Exchange Server 2013 Cumulative Update 6 and onwards:
HM Worker is responsible for maintaining the password for Monitoring mailboxes. HM worker uses a complex algorithm to generate password to be used for monitoring mailbox. The password for monitoring mailbox is reset under the following conditions:
However, the mailboxes listed above may not be associated with the server on which database is hosted. As explained in creation logic, the name of Client Access Server or the mailbox database is important in searching for monitoring mailbox associated and in creation of monitoring mailbox.
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 an Office 365 shared mailbox size report.
This report helps to analyze the storage growth of Exchange Online shared mailboxes. Also, you can identify mailboxes that are nearing its full storage capacity with details like mailbox size, used percentage, item count, and size growth by daily usage.
The AdminDroid Exchange Online reporting tool provides comprehensive data to check shared mailbox 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!
The default size of Microsoft 365 mailboxes varies based on the mailbox type and user subscription. The default size of a user mailbox is either 50 GB or 100 GB, and when the space is exhausted, users won't be able to send or receive emails. To avoid this, admins need to keep a check on the mailbox size.
The Mailbox Usage report provided by the Admin Center shows only the storage space consumed by user mailboxes. To view the actual user mailbox size, shared mailbox size, resource mailbox usage, and other mailbox related details you have to navigate to the Exchange Admin Center (EAC).
Apart from the aforementioned reports, the tool also provides reports that provide every day mailbox usage statistics. Unlike Microsoft 365 Admin Center, M365 Manager Plus reports on all types of mailboxes from a single window.
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